Science/Chemistry question:

[Pszemol]

Let's assume we have relativelly high level of phosphates in
the 58 gallon tank. There are three ways to deal with the problem:
- partial water exchange with let's say 12 gallons water with no phosphates
- usage of phosphate removal media like PhosBan, Phosar etc...
- partial water change AND phosphate removal filters.

Intuition would tell me that the third option will be most effective.
But what to do first? Should I put phosphate removal medium and
extract as much phosphate as phosban is able to and then change water?
Or maybe do water change first, and then lowered phosphate levels
treat with the phosban? Or maybe it does not really matter?

[KurtG]

Pszemol wrote:
> Let's assume we have relativelly high level of phosphates in
> the 58 gallon tank. There are three ways to deal with the problem:
> - partial water exchange with let's say 12 gallons water with no phosphates
> - usage of phosphate removal media like PhosBan, Phosar etc...
> - partial water change AND phosphate removal filters.
>
> Intuition would tell me that the third option will be most effective.
> But what to do first? Should I put phosphate removal medium and
> extract as much phosphate as phosban is able to and then change water?
> Or maybe do water change first, and then lowered phosphate levels
> treat with the phosban? Or maybe it does not really matter?

btw, it also drive me nuts when the recommendation is to "replace your
evaporated water first" then do a water change. You want to suck out
waste water at it's highest concentrations and then refill will both
salt and fresh water to get you back to your SG. Of course, that's why
I use two trash cans rather then one.

But, to each their own... You can always use larger or more frequent
water changes to accomplish the same level of exchange, but it seems
like a waste of salt and effort to me.

--Kurt

[George Patterson]

Pszemol wrote:

> But what to do first? Should I put phosphate removal medium and
> extract as much phosphate as phosban is able to and then change water?
> Or maybe do water change first, and then lowered phosphate levels
> treat with the phosban? Or maybe it does not really matter?

Do the water change first. According to the info that comes with RowaPhos, the
contents of the package will remove a certain amount of phosphates. When used in
a phosphate reactor or filter, you just leave it there until phosphate levels
start to rise again. If the phosphate level in the tank is lower due to a recent
water change, the RowaPhos will last longer. I assume that this would also be
true of other phosphate removers, such as Phosban.

George Patterson
If you torture the data long enough, eventually it will confess
to anything.

[Pszemol]

"George Patterson" > wrote in message news:0IzJh.2285$8u4.690@trnddc08...
> Do the water change first. According to the info that comes with RowaPhos, the
> contents of the package will remove a certain amount of phosphates. When used in
> a phosphate reactor or filter, you just leave it there until phosphate levels
> start to rise again. If the phosphate level in the tank is lower due to a recent
> water change, the RowaPhos will last longer. I assume that this would also be
> true of other phosphate removers, such as Phosban.

The problem is that I noticed phosphates do not go below 0.05 in my tank.
I do not know if this is the lowest level PhosAr can pull them down or
it is simply not efficient enough... Maybe I need to replace it with a larger
amount of media in the reactor. Right now I use about 50 grams of PhosAR
in my 58 gallons reef placed in a Phosban Reactor powered with MaxiJet900.

If the 0.05 was the lowest level achievable with the phosphate removal
than it would be sensible to use new remover first, bring phosphates
down to 0.05 and then do a water change to bring them even lower :-)

[George Patterson]

KurtG wrote:

> btw, it also drive me nuts when the recommendation is to "replace your
> evaporated water first" then do a water change. You want to suck out
> waste water at it's highest concentrations and then refill will both
> salt and fresh water to get you back to your SG.

And I'm the opposite. I mix up my salt water to the correct SG, drain my tank
down to a specific point on the glass (ie. 25 gallons low), and add the new
water to top it back off. If the water level in the tank is low before the
change, I won't actually be draining off 25 gallons, and the SG will be a bit
high after the water change. It could get quite high after several water changes.

George Patterson
If you torture the data long enough, eventually it will confess
to anything.

[Pszemol]

"KurtG" > wrote in message ...
> btw, it also drive me nuts when the recommendation is to "replace your
> evaporated water first" then do a water change. You want to suck out
> waste water at it's highest concentrations and then refill will both
> salt and fresh water to get you back to your SG. Of course, that's why
> I use two trash cans rather then one.

Recomendations are just that: recomendations... :-)
You do not have to follow recomendations if you KNOW WHAT YOU ARE DOING :-)
And in this case you are of course right. I do a water change first,
I use empty Instant Ocean salt buckets. I prepare two full of sal****er
and use third for drain. If you replace same amount of concentrated
water with diluted one your salinity will drop, so you need to drain
little less old water to replace it with the new...

It takes some practice, so for beginners recomendation is good: after
replacing evaporated water and bringing salinity to normal you simply
replace same amounts of old water with new water and salinity stays unchanged.

> But, to each their own... You can always use larger or more frequent
> water changes to accomplish the same level of exchange, but it seems
> like a waste of salt and effort to me.

Exactly - larger water changes are simply much more effective.
And this is not linear equation: replacing twice 10% of water
does not equal one 20% water change. 20% is much more effective.

[George Patterson]

Pszemol wrote:

> The problem is that I noticed phosphates do not go below 0.05 in my tank.
> I do not know if this is the lowest level PhosAr can pull them down or
> it is simply not efficient enough... Maybe I need to replace it with a
> larger
> amount of media in the reactor.

Perhaps there would always be a trace due to dead spots in the tank (water that
never gets pulled through the reactor).

George Patterson
If you torture the data long enough, eventually it will confess
to anything.

[KurtG]

George Patterson wrote:
> drain my
> tank down to a specific point on the glass (ie. 25 gallons low),

Yep, it's less efficient, but it does enable the mark on the tank
technique which seems to be more or less standard based on every book
I've read.

I opted against this for two reasons:

1- less efficient at removing waste as you're diluting your tank before
draining a percentage.

2- what if you over drain by accident? If you have enough extra salt
water, you're in luck; otherwise, you're mixing up more salt water.

3- you're limited to draining only xx%. What if you want to do lower
cleaning and/or more siphon cleaning?

I'd rather keep it a bucket and use it for make up (if needed) after the
silt settles a bit. If you do that, there's no advantage to the mark on
the tank technique and a few disadvantages.

I guess it's less of a big deal now as I keep my evaporative makeup at
less then a gallon.

--Kurt

[Add Homonym]

George Patterson wrote:
> KurtG wrote:
>
>> btw, it also drive me nuts when the recommendation is to "replace your
>> evaporated water first" then do a water change. You want to suck out
>> waste water at it's highest concentrations and then refill will both
>> salt and fresh water to get you back to your SG.
>
>
> And I'm the opposite. I mix up my salt water to the correct SG, drain my
> tank down to a specific point on the glass (ie. 25 gallons low), and add
> the new water to top it back off. If the water level in the tank is low
> before the change, I won't actually be draining off 25 gallons, and the
> SG will be a bit high after the water change. It could get quite high
> after several water changes.
>
> George Patterson
> If you torture the data long enough, eventually it will confess
> to anything.


Huh?

Don't see what advantage there is to that - what advantage does having a
25G low mark give you?

Do you generally only have 25 Gal available to replace with?

I do it this way-

take water out, THEN adjust SG to norm, THEN refill with new sal****er.

I do many many micro changes (plus I only have a 20 gal nano anyway...)
so I never thought about putting a mark for a specific amount to drain.

I recently started doing 1/4 gallon (ie: 1 qt) change per day, every
day, on schedule at 11:00 pm before I go to bed -- part of my nightime
routine -- comes right after "brush teeth" on the checklist. seems to
work quite well for a small tank - I can do the wtare change in under 30
seconds using a plastic 1 qt measuri8ng cup.

[KurtG]

George Patterson wrote:
> Do the water change first.

I wonder what happened to my other post, but I agree with George. You
want to export as much Phosphate as possible with the water change, so
you do that before starting the phosphate reactor. The reactor is a
much slower process.

--Kurt

[Wayne Sallee]

Actually the only thing that you are accomplishing,
is that you are waisting less RO water. That's the
only thing that you are accomplishing.

If you do a 15% water change, then you are still
doing a 15% water change even if the water is more
concentrated.

If you add 30 gallons worth of sea water strength
water, or it's equivalent value of diluted strength,
you are still only removing from your tank a 30
gallon equivalent of phosphate.

Wayne Sallee
Wayne's Pets


KurtG wrote on 3/13/2007 11:51 AM:
> George Patterson wrote:
>> drain my
>> tank down to a specific point on the glass (ie. 25 gallons low),
>
> Yep, it's less efficient, but it does enable the mark on the tank
> technique which seems to be more or less standard based on every book
> I've read.
>
> I opted against this for two reasons:
>
> 1- less efficient at removing waste as you're diluting your tank before
> draining a percentage.
>
> 2- what if you over drain by accident? If you have enough extra salt
> water, you're in luck; otherwise, you're mixing up more salt water.
>
> 3- you're limited to draining only xx%. What if you want to do lower
> cleaning and/or more siphon cleaning?
>
> I'd rather keep it a bucket and use it for make up (if needed) after the
> silt settles a bit. If you do that, there's no advantage to the mark on
> the tank technique and a few disadvantages.
>
> I guess it's less of a big deal now as I keep my evaporative makeup at
> less then a gallon.
>
> --Kurt

[Wayne Sallee]

George is right, unless your suspicion of lowest
concentration theory is correct. But I don't think
that your lowest concentration theory is correct.
But why not find out if it is correct. Get a jar of
aquarium water, and test it for phosphates, then get
a new bag of phosphate remover, and place it in the
jar. Then give it time to pull the phosphates out,
and then test the water.

Wayne Sallee
Wayne's Pets


Pszemol wrote on 3/13/2007 11:14 AM:
> "George Patterson" > wrote in message
> news:0IzJh.2285$8u4.690@trnddc08...
>> Do the water change first. According to the info that comes with
>> RowaPhos, the contents of the package will remove a certain amount of
>> phosphates. When used in a phosphate reactor or filter, you just leave
>> it there until phosphate levels start to rise again. If the phosphate
>> level in the tank is lower due to a recent water change, the RowaPhos
>> will last longer. I assume that this would also be true of other
>> phosphate removers, such as Phosban.
>
> The problem is that I noticed phosphates do not go below 0.05 in my tank.
> I do not know if this is the lowest level PhosAr can pull them down or
> it is simply not efficient enough... Maybe I need to replace it with a
> larger
> amount of media in the reactor. Right now I use about 50 grams of PhosAR
> in my 58 gallons reef placed in a Phosban Reactor powered with MaxiJet900.
>
> If the 0.05 was the lowest level achievable with the phosphate removal
> than it would be sensible to use new remover first, bring phosphates
> down to 0.05 and then do a water change to bring them even lower :-)

[George Patterson]

KurtG wrote:

> 2- what if you over drain by accident? If you have enough extra salt
> water, you're in luck; otherwise, you're mixing up more salt water.

I wouldn't worry about this one; I've used my technique for about 30 years and
never had this happen.

George Patterson
If you torture the data long enough, eventually it will confess
to anything.

[George Patterson]

Add Homonym wrote:

> Do you generally only have 25 Gal available to replace with?

Yes. I make up 25 gallons at a time.

George Patterson
If you torture the data long enough, eventually it will confess
to anything.

[Inabón Yunes]

I don't think I follow your point.
The guy wants to know if he should use a phosphate remover before or after
the water change. Then the topic changed to volumes and everyone was on
topic.
I am sure that performing a water change before adding any remover is the
only way to go.
I understood every reply posted, then you came along!
Either you didn't write what you were thinking or you were drinking before
posting.
It just doesn't make sense.
A 15% water change of "concentrated" water (I will assume you meant with a
high reading of PO4) you claim that is the same 30 gallons of diluted water?
You must be on drugs!
If this isn't what you meant I am sorry but you have us used to the most
ridiculous comments.
Now, read this again and tell us what it means...

"If you add 30 gallons worth of sea water strength water, or it's equivalent
value of diluted strength, you are still only removing from your tank a 30
gallon equivalent of phosphate."

In Mexico that is called a CANTINFLADA. Any Mexican here will know what I
am talking about. (BTW, I am not Mexican but like Cantinflas the comedian)

iy

"Wayne Sallee" > wrote in message
ink.net...
> Actually the only thing that you are accomplishing, is that you are
> waisting less RO water. That's the only thing that you are accomplishing.
>
> If you do a 15% water change, then you are still doing a 15% water change
> even if the water is more concentrated.
>
> If you add 30 gallons worth of sea water strength water, or it's
> equivalent value of diluted strength, you are still only removing from
> your tank a 30 gallon equivalent of phosphate.
>
> Wayne Sallee
> Wayne's Pets
>
>
> KurtG wrote on 3/13/2007 11:51 AM:
>> George Patterson wrote:
>>> drain my
>>> tank down to a specific point on the glass (ie. 25 gallons low),
>>
>> Yep, it's less efficient, but it does enable the mark on the tank
>> technique which seems to be more or less standard based on every book
>> I've read.
>>
>> I opted against this for two reasons:
>>
>> 1- less efficient at removing waste as you're diluting your tank before
>> draining a percentage.
>>
>> 2- what if you over drain by accident? If you have enough extra salt
>> water, you're in luck; otherwise, you're mixing up more salt water.
>>
>> 3- you're limited to draining only xx%. What if you want to do lower
>> cleaning and/or more siphon cleaning?
>>
>> I'd rather keep it a bucket and use it for make up (if needed) after the
>> silt settles a bit. If you do that, there's no advantage to the mark on
>> the tank technique and a few disadvantages.
>>
>> I guess it's less of a big deal now as I keep my evaporative makeup at
>> less then a gallon.
>>
>> --Kurt

[Add Homonym]

Inabón Yunes wrote:
> I don't think I follow your point.
> The guy wants to know if he should use a phosphate remover before or after
> the water change. Then the topic changed to volumes and everyone was on
> topic.
> I am sure that performing a water change before adding any remover is the
> only way to go.

Indeed it is. Wayne is usually dead on right with most (all?) of what he
says. I think maybe he just had a brain fart here?

> I understood every reply posted, then you came along!
> Either you didn't write what you were thinking

That'd be my guess.

> or you were drinking before
> posting.

HEY! Ad Hominem arguments are my bag. Knock it off!

> It just doesn't make sense.

No, it didn't. So? Not the first time to happen on usenet.

> A 15% water change of "concentrated" water (I will assume you meant with a
> high reading of PO4) you claim that is the same 30 gallons of diluted water?

Yup.

> You must be on drugs!

He goofed. So therefore he is on drugs? Heh. If you are going to resort
to ad hominem attacks, at least make them convincing.

> If this isn't what you meant I am sorry but you have us used to the most
> ridiculous comments.
> Now, read this again and tell us what it means...
>
> "If you add 30 gallons worth of sea water strength water, or it's equivalent
> value of diluted strength, you are still only removing from your tank a 30
> gallon equivalent of phosphate."
>
> In Mexico that is called a CANTINFLADA. Any Mexican here will know what I
> am talking about. (BTW, I am not Mexican but like Cantinflas the comedian)
>
> iy
>
> "Wayne Sallee" > wrote in message
> ink.net...
>
>>Actually the only thing that you are accomplishing, is that you are
>>waisting less RO water. That's the only thing that you are accomplishing.
>>
>>If you do a 15% water change, then you are still doing a 15% water change
>>even if the water is more concentrated.
>>
>>If you add 30 gallons worth of sea water strength water, or it's
>>equivalent value of diluted strength, you are still only removing from
>>your tank a 30 gallon equivalent of phosphate.
>>
>>Wayne Sallee
>>Wayne's Pets

>>
>>KurtG wrote on 3/13/2007 11:51 AM:
>>
>>>George Patterson wrote:
>>>
>>>>drain my
>>>>tank down to a specific point on the glass (ie. 25 gallons low),
>>>
>>>Yep, it's less efficient, but it does enable the mark on the tank
>>>technique which seems to be more or less standard based on every book
>>>I've read.
>>>
>>>I opted against this for two reasons:
>>>
>>>1- less efficient at removing waste as you're diluting your tank before
>>>draining a percentage.
>>>
>>>2- what if you over drain by accident? If you have enough extra salt
>>>water, you're in luck; otherwise, you're mixing up more salt water.
>>>
>>>3- you're limited to draining only xx%. What if you want to do lower
>>>cleaning and/or more siphon cleaning?
>>>
>>>I'd rather keep it a bucket and use it for make up (if needed) after the
>>>silt settles a bit. If you do that, there's no advantage to the mark on
>>>the tank technique and a few disadvantages.
>>>
>>>I guess it's less of a big deal now as I keep my evaporative makeup at
>>>less then a gallon.
>>>
>>>--Kurt
>
>
>

[Wayne Sallee]

I was replying to Kurt's response to the response to
his post that follows: (in other words go up two
posts in the thread and you will see:)

###################
btw, it also drive me nuts when the recommendation
is to "replace your
evaporated water first" then do a water change. You
want to suck out
waste water at it's highest concentrations and then
refill will both
salt and fresh water to get you back to your SG. Of
course, that's why
I use two trash cans rather then one.

But, to each their own... You can always use larger
or more frequent
water changes to accomplish the same level of
exchange, but it seems
like a waste of salt and effort to me.

--Kurt
############################################

Inabón Yunes wrote on 3/14/2007 1:47 PM:
> I don't think I follow your point.
> The guy wants to know if he should use a phosphate remover before or after
> the water change. Then the topic changed to volumes and everyone was on
> topic.
> I am sure that performing a water change before adding any remover is the
> only way to go.
> I understood every reply posted, then you came along!
> Either you didn't write what you were thinking or you were drinking before
> posting.
> It just doesn't make sense.
> A 15% water change of "concentrated" water (I will assume you meant with a
> high reading of PO4) you claim that is the same 30 gallons of diluted water?
> You must be on drugs!
> If this isn't what you meant I am sorry but you have us used to the most
> ridiculous comments.
> Now, read this again and tell us what it means...
>
> "If you add 30 gallons worth of sea water strength water, or it's equivalent
> value of diluted strength, you are still only removing from your tank a 30
> gallon equivalent of phosphate."
>
> In Mexico that is called a CANTINFLADA. Any Mexican here will know what I
> am talking about. (BTW, I am not Mexican but like Cantinflas the comedian)
>
> iy
>
> "Wayne Sallee" > wrote in message
> ink.net...
>> Actually the only thing that you are accomplishing, is that you are
>> waisting less RO water. That's the only thing that you are accomplishing.
>>
>> If you do a 15% water change, then you are still doing a 15% water change
>> even if the water is more concentrated.
>>
>> If you add 30 gallons worth of sea water strength water, or it's
>> equivalent value of diluted strength, you are still only removing from
>> your tank a 30 gallon equivalent of phosphate.
>>
>> Wayne Sallee
>> Wayne's Pets
>>
>>
>> KurtG wrote on 3/13/2007 11:51 AM:
>>> George Patterson wrote:
>>>> drain my
>>>> tank down to a specific point on the glass (ie. 25 gallons low),
>>> Yep, it's less efficient, but it does enable the mark on the tank
>>> technique which seems to be more or less standard based on every book
>>> I've read.
>>>
>>> I opted against this for two reasons:
>>>
>>> 1- less efficient at removing waste as you're diluting your tank before
>>> draining a percentage.
>>>
>>> 2- what if you over drain by accident? If you have enough extra salt
>>> water, you're in luck; otherwise, you're mixing up more salt water.
>>>
>>> 3- you're limited to draining only xx%. What if you want to do lower
>>> cleaning and/or more siphon cleaning?
>>>
>>> I'd rather keep it a bucket and use it for make up (if needed) after the
>>> silt settles a bit. If you do that, there's no advantage to the mark on
>>> the tank technique and a few disadvantages.
>>>
>>> I guess it's less of a big deal now as I keep my evaporative makeup at
>>> less then a gallon.
>>>
>>> --Kurt
>
>

[Add Homonym]

Wayne Sallee wrote:
> I was replying to Kurt's response to the response to his post that
> follows: (in other words go up two posts in the thread and you will see:)
>
> ###################
> btw, it also drive me nuts when the recommendation is to "replace your
> evaporated water first" then do a water change. You want to suck out
> waste water at it's highest concentrations and then refill will both
> salt and fresh water to get you back to your SG. Of course, that's why
> I use two trash cans rather then one.
>
> But, to each their own... You can always use larger or more frequent
> water changes to accomplish the same level of exchange, but it seems
> like a waste of salt and effort to me.
>
> --Kurt
> ############################################

And Kurt is right, in this case. You WILL be removing more pollutants if
you do it this way (or alternately using less salt, if compared to what
you'd get if you top off first and remove enough water to take out the
same pollutants as if you removed water before you topped off)

[Wayne Sallee]

I don't think so.

Assuming: "1/2 cup of salt per gallon of salt water
rule of thumb".

Assuming: 30 gallons of salt water made up to
regular strength using the "1/2 cup rule" as being
the standard for the test.

Assuming: 30 gallons of regular strength water
having to be taken out for a standard water change.

Assuming: a tank size of 60 gallons.

Now for the test tank Assumptions ###########

Assuming: 5 gallons of evaporation.

Assuming: 27.5 gallons of extra salty water taken
out of the tank. After evaporation, your tank now
holds 55 gallons of water, and a 50% water change is
27.5 gallons. This 27.5 gallons of strong water is
equivalent to 30 gallons of normal strength water.

Assuming: 30 gallons of regular strength water being
added plus 5 gallons of RO water to make up for
evaporation.

Discussion #########################

In both the test, and the control you are doing a
50% water change. You are changing 50% of the salt,
then obviously you will be changing 50% of the
phosphates.

If you change larger amounts in the test, then you
are doing more than a 50% water change, and you are
making more than 30 gallons of regular strength water.

Wayne Sallee
Wayne's Pets


Add Homonym wrote on 3/14/2007 2:33 PM:
> And Kurt is right, in this case. You WILL be removing more pollutants if
> you do it this way (or alternately using less salt, if compared to what
> you'd get if you top off first and remove enough water to take out the
> same pollutants as if you removed water before you topped off)
>

[swarvegorilla]

"Pszemol" > wrote in message
...
> Let's assume we have relativelly high level of phosphates in
> the 58 gallon tank. There are three ways to deal with the problem:
> - partial water exchange with let's say 12 gallons water with no
> phosphates
> - usage of phosphate removal media like PhosBan, Phosar etc...
> - partial water change AND phosphate removal filters.
>
> Intuition would tell me that the third option will be most effective.
> But what to do first? Should I put phosphate removal medium and
> extract as much phosphate as phosban is able to and then change water?
> Or maybe do water change first, and then lowered phosphate levels
> treat with the phosban? Or maybe it does not really matter?


Ya know I'd prob just throw a fbf filled with purigen on the tank.
keep doing whatever you were doing before and see how it clears up.

[Add Homonym]

Wayne Sallee wrote:
> I don't think so.
>
> Assuming: "1/2 cup of salt per gallon of salt water rule of thumb".
>
> Assuming: 30 gallons of salt water made up to regular strength using the
> "1/2 cup rule" as being the standard for the test.
>
> Assuming: 30 gallons of regular strength water having to be taken out
> for a standard water change.
>
> Assuming: a tank size of 60 gallons.
>
> Now for the test tank Assumptions ###########
>
> Assuming: 5 gallons of evaporation.
>
> Assuming: 27.5 gallons of extra salty water taken out of the tank. After
> evaporation, your tank now holds 55 gallons of water, and a 50% water
> change is 27.5 gallons. This 27.5 gallons of strong water is equivalent
> to 30 gallons of normal strength water.
>

There in lies the flaw in your logic. One would not be taking out 27.5 -
one would still be taking out 30.

Therefore, one would be removing more phosphate, nitrate, etc.

[George Patterson]

Add Homonym wrote:

> And Kurt is right, in this case. You WILL be removing more pollutants if
> you do it this way (or alternately using less salt, if compared to what
> you'd get if you top off first and remove enough water to take out the
> same pollutants as if you removed water before you topped off)

I always prefer to plug in some numbers as an example. Let's say that I have a
100 liter tank (actual water capacity), my nitrate level is 30 mg/l, and I
decide to make a 25 liter water change. My SG is pretty high and water level is
down to 95 liters, so I actually only have to drain 20 liters. That removes 600
mg of nitrates. There is now 2250 mg of nitrates remaining in the tank. After
adding 25 liters of new water, the nitrate level will be 22.5 mg/l.

Now. Say I top off the water level first. I've diluted the nitrates, so my
nitrate level is now 28.5 mg/l. Draining 25 liters will remove 712.5 mg of
nitrates, leaving 2137.5 mg of nitrates in the tank. After adding the new water,
the nitrate level will be 21.375 mg/l.

George Patterson
If you torture the data long enough, eventually it will confess
to anything.

[Wayne Sallee]

Did you read everything, or did you stop reading at
this point?

Wayne Sallee
Wayne's Pets


Add Homonym wrote on 3/15/2007 9:01 AM:
> Wayne Sallee wrote:
>> I don't think so.
>>
>> Assuming: "1/2 cup of salt per gallon of salt water rule of thumb".
>>
>> Assuming: 30 gallons of salt water made up to regular strength using
>> the "1/2 cup rule" as being the standard for the test.
>>
>> Assuming: 30 gallons of regular strength water having to be taken out
>> for a standard water change.
>>
>> Assuming: a tank size of 60 gallons.
>>
>> Now for the test tank Assumptions ###########
>>
>> Assuming: 5 gallons of evaporation.
>>
>> Assuming: 27.5 gallons of extra salty water taken out of the tank.
>> After evaporation, your tank now holds 55 gallons of water, and a 50%
>> water change is 27.5 gallons. This 27.5 gallons of strong water is
>> equivalent to 30 gallons of normal strength water.
>>
>
> There in lies the flaw in your logic. One would not be taking out 27.5 -
> one would still be taking out 30.
>
> Therefore, one would be removing more phosphate, nitrate, etc.