11% 2x per week or 22% 1x per week

Talking about water changes of course. Now that I've got my bio filter
built back up, I'm thinking about going to 11% changes twice per week. Is
that any better or worse than 22% once per week? I can actually see a few
advantages and disadvantages to both.

Thanks in advance!

go with the 22% or even better is closer to 50%

I just read up on this today so bear with me while I try to explain just
using 10% vs 50%

In a 100 gallon tank just changing 10% a week
(amount of oldest water removed per change)

1st week = 10 gallons
2nd week = 9 gallons
3rd week = 8.1 g
4th week = 7.29 g
5th week = 6.46 g
6th week = 5.81 g
7th week = 5.23 g
8th week = 4.71 g

Ok as you can see even after 8 weeks of 10% water changes you have only
removed a total of 56.61 g of the oldest water but still have 43.39 g of
old water still in the tank. Now if you look at the same thing, but
using 50% you can see a big difference.

1st week = 50 g
2nd week = 25 g
3rd week = 12.5 g
4th week = 6.25 g
5th week = 3.12 g
6th week = 1.56 g
7th week = 0.78 g
8th week = 0.39 g

Now you have removed a total of 99.61 g of the oldest water and only
have 0.40 g of old water left in the tank.

Think about it this way tho. If your toilet backs up you can leave the
room. Fish don't have that luxury.

Vicki

Got my info from a book called "The simple guide to freshwater
Aquariums" by David Boruchowitz

I did not say it was my math but info from a book. The original
parameters were for 11% or 22%. I just used the books info on 10 and
50%

I have always been a 50%er anyways.

Vicki

"~Vicki ~" wrote in message
...
I did not say it was my math but info from a book. The original
parameters were for 11% or 22%. I just used the books info on 10 and
50%

I have always been a 50%er anyways.

Vicki

I know people who do 100% changes and because they do it often, it works.
Doing 50% will also work, if it's done at a frequency which would prevent
any significant build-up since the last change (IMO). The only problem
with these massive changes is when the interval gets too long, - such
that the difference in parameters now becomes stressful. It's also not
possible with freshly drawn well water. Letting the interval frequency
slide is not uncommon with new hobbyists, so 50% would become more
problematic for them. IMHO, if you can do 50% at short intervals, then
the short interval might preclude the requirement to do such a large
water change ;~)

Having said all that, I'm a firm believer that aquariums are like
preparing fine meals. There are many recipes to success.

NetMax

"NetMax" wrote in message
.. .

"~Vicki ~" wrote in message
...
I did not say it was my math but info from a book. The original
parameters were for 11% or 22%. I just used the books info on 10
and
50%

I have always been a 50%er anyways.

Vicki

I know people who do 100% changes and because they do it often, it
works.
Doing 50% will also work, if it's done at a frequency which would
prevent
any significant build-up since the last change (IMO). The only
problem
with these massive changes is when the interval gets too long, - such
that the difference in parameters now becomes stressful. It's also
not
possible with freshly drawn well water. Letting the interval
frequency
slide is not uncommon with new hobbyists, so 50% would become more
problematic for them. IMHO, if you can do 50% at short intervals,
then
the short interval might preclude the requirement to do such a large
water change ;~)

Having said all that, I'm a firm believer that aquariums are like
preparing fine meals. There are many recipes to success.

NetMax



Without a TDS/conductivity meter its just going to be guesswork.....I
have one and I know precisely when and how much water to change so my
fish do not get shocked and I do not have unhealthy build-ups....well
maybe I do sometimes.....but I know about it though...........

A discus guy did an experiment comparing fry growth relative to water
change frequency. Daily 50% and weekly 50% was compared for the growth
cycle of fry from 1 inch to 4 inches. The results, no difference.
There was plenty of facts and values and all that....but in the
end....no difference. So some build-up of waste..etc.... in the water
was deemed ok.

"Fish Heads" wrote in message
...
Talking about water changes of course. Now that I've got my bio filter
built back up, I'm thinking about going to 11% changes twice per week. Is
that any better or worse than 22% once per week? I can actually see a few
advantages and disadvantages to both.

If you have the time, I'd change less water more often. More stable tank
chemistry that way.


Graham.

Without a TDS/conductivity meter its just going to be guesswork.....I
have one and I know precisely when and how much water to change so my
fish do not get shocked and I do not have unhealthy build-ups....well
maybe I do sometimes.....but I know about it though...........

Okay, I'll admit ignorance. Why is a TDS/conductivity meter such an
essential tool? Surely, not all dissolved solids/conductive ions are
harmful to fish. How would the readings be interpreted if used in a tank
with hard water or added salt? Is it more meaningful to concentrate on
reducing dissolved solids rather than reducing NOx and NHx?

-coelacanth

i too believe in the less-water, more-often method
i'm doing 3%/day
i set up my tank w/ a drip feed from ro/di unit
& an overflow cut in the side that's tied in to the sewer lines of my house
i can see where hooking up to house plumping could be a bit of a challange for most
but i was lucky in that i have a basement w/ suspended ceilings

"coelacanth"

SNIP
wrote Is it more meaningful to concentrate on
reducing dissolved solids rather than reducing NOx and NHx?

-coelacanth

Probably not ..... It is just another tool.

TDS is like lots of other water parameters. Some fish do best in certain
ranges others may not care much. Abrupt changes of any of the parameters
are rough on fish. TDS is a garbage can term..... it maters just as much
WHAT is in the can as it does HOW MUCH is in the can. Obviously some things
are more toxic than others.

In the environmental business TDS and all the rest aren't the final test....
The fish kill test is the one that determines if the water you are dumping
is "OK" to the EPA. It is the measure real life toxicity test. Rainbow
trout are really touchy, a variety of others minnows less so. The first
test I ever had to run had 100% survival in the test tank and 60% survival
in the supposedly clean water standard tank. Rough life for test fish, but
the EPA thinks it is cool.

On topic, TDS is a good cheap test to monitor over all water quality
changes. pH, kH, gH and all the rest don't count for much if the other
dissolved materials reach a toxic level. I suspect osmotic shock is just as
much a killer as the rest. Obviously any of them in combination will wipe
out a fish. They are inter-related to a point. I would assume TDS to
increase with higher kH and gH, however TDS may not reflect TOC (total
organic carbon) which reflects the amount of Organics in the soup. I'm sure
dissolved ionic compounds like salt have a greater effect on TDS than a more
charge neutral organic compound, after all a TDS meter measures the
conductivity (the ease with which electricity passes through the liquid) but
doesn't really tell you what the dissolved material is.

During my oilfield days, we used conductivity as measured by wireline
logging equipment to calculate oil saturations. Most places we assumed
conductivity was all due to salt (NaCl), but I did a lot of work in "fresh
water" country where you had to use a whole bunch of fudge factors to make
the standard equations work. I ramble... but the point is conductivity
measures ease of movement of electrons..... TDS is related to that, neither
tell you what is in the water, so you need to check all the parameters once
in a while.

Bob

Having said all that, I'm a firm believer that aquariums are like
preparing fine meals. There are many recipes to success.
NetMax




Thank you. And you are absolutely right there.
(ask me for my brownie recipe one day

Vicki