DIY Coil Denitrator Questions

[Kveill]

I have been looking at different DIY plan for Coil Denitrators and I was
wondering if anyone has had any luck building one of these things. I am
really curious what kind of pump and flow rate did you use. Can anyone make
any recomendations or give me specific directions on how to build one? Any
information will be apprecitated.

From what I have heard you should get a some PVC pipe 3-4" diameter and run
75-100ft of 1/4in clear tubing around and fill the middle of the tube with
bio-balls. Then you should let the output drip at 1 drop/sec until the unit
has cycled then you can open it up to flow at full speed once the unit has
cycled. I have heard of cycle time between 6-8 weeks. Does this sound about
right? Thanks

[Iain Miller]

"Kveill" > wrote in message
...
> I have been looking at different DIY plan for Coil Denitrators and I was
> wondering if anyone has had any luck building one of these things. I am
> really curious what kind of pump and flow rate did you use. Can anyone
make
> any recomendations or give me specific directions on how to build one? Any
> information will be apprecitated.
>
> From what I have heard you should get a some PVC pipe 3-4" diameter and
run
> 75-100ft of 1/4in clear tubing around and fill the middle of the tube with
> bio-balls. Then you should let the output drip at 1 drop/sec until the
unit
> has cycled then you can open it up to flow at full speed once the unit has
> cycled. I have heard of cycle time between 6-8 weeks. Does this sound
about
> right? Thanks
>

You are on the right lines. I looked at building one but eventually bought
one of these....

http://www.shopsolution.nl/shop/home.asp?shopid=seameuk&prodid=ratznitrateragrade

The way all nitrate filters work is to encourage an oxygen free environment
in which Anaerobic bacteria will grow & live - they feed off the Nitrate.
You get this by passing water through them very slowly. The reason I went
for the Sulphur based filter was that there is a school of thought that says
that you need to feed "normal" de-nitrators with Methanol for them to work
properly. The sulphur is an alternative to this in that the bactreria will
feed of it instead - or so the story goes. I also decided that for the price
it was not worth messing about trying to build something with all the risks
of leaking cannisters etc.

As far as commissioning it is concerned it helps to give it water that is as
clean as possible and as oxygen depleted as possible. That means that you
(ideally) take a feed from the output side of a cannister filter. The water
goes through the cannister and the Aerobic bacteria in there deal with the
ammonia & nitrites as normal & in so doing deplete the water of oxygen.

You then run a bypass off the output of the cannister with a valve of some
kind so you can control the flow through the denitrator - the remainder just
goes straight back to the tank.

The instructions with mine say to run it at 1 drop /second for a week or so
(or until the water coming out of it is Nitrite and Nitrate free), then
increase to 2 drops a second till its clear again and then 4 drops a second
& then gradually on upwards to a maximum of about 10 litres an hour. The
final amount you can get to will depend on the size of the filter you have.

What actually happens (I think) is that in the first part of the filter you
get an Aerobic bacteria colony (as you would in any filter) and then
gradually the Anaerobic colony builds up in the last part of the filter. If
you increase the flow rate too quickly the first colony is not big enough to
fully deplete the water of oxygen and so the second colony doesn't take hold
properly, the thing breaks down and you have to start again.

The answer to your question is that you need to build the flow up gradually
over a number of weeks - you can not commission it at 1 drop a second and
then crank it up to full flow.

You also need to be aware of a few other things

1) The filter seems to strip the buffer out of the water causing the Kh (and
therefore Ph) to drop. Eventually this could cause a Ph crash in your tank
if left unchecked so I have been adding some sodium Bicarb to the tank a
couple of times a week to compensate (you could put a few marble chips in
your filter instead). If you have very soft (low Kh) water to start with
you'd need to watch this quite carefully.

2) As the filter builds up (and particularly in the first week or so) you
can find that the water coming out of it is VERY high in both Nitrites and
Nitrates - you need to keep an eye on this but it will pass soon enough. I
got this effect after I increased the flow rate for the first time - I went
too far. I stabilised the thing by slowing it down a bit.

3) If you run the thing too slowly (or let it stop for any period of time)
then it can go bad & you will get Hydrogen Sulphide (rotten eggs) out of
it - that would not do your tank any good at all! (I have detected a faint
whiff of this once or twice & when I did just increased the flow a tiny
bit).

All sounds a bit daunting but actually its not and mine is now beginning to
kick in nicely. I am upto 4 or 5 drops a second. As you increase the rate &
it starts to establish it seems to be less fiddly & sensisitive - I would
guess because the bacterial colony is becoming well established if that
makes sense.

In total you do not need a very high flow rate to keep nitrates under
control. WHen its working it absolutely strips the nitrates from the water -
they are simply not detectable at all. My tank is about 70 UK gallons (
85-90 USG) & I think that a flow rate of under 1 Gallon per hour will be
more than enough to ultimately reduce my nitrates to zero - which I don't
actually want to do because I have plants in the tank!

Hope that helps - come back if you have any more questions & I'll try to
answer them

rgds

I.

[Iain Miller]

> expect the output to have low ph, its not perminent and only requires gas
exchange to
> bring the ph back up to what the tank level is.

I'm interested in this....as per my other post, what I have found (tested)
is that the water coming out the Nitrate filter has a very much Lower Kh
than when it went in. This would explain why the Ph is lower since Kh & ph
run in the same direction given a constant level of CO2. What I'm not sure
of though is that the change is only temporary (or why its happening at
all!) - but it seems pretty permanent from what I've found - i.e. over the
course of a week to 10 days the Kh in my tank dropped away quite
considerably. I am intersted to know however as to whether this will be a
permanent side effect of using the Nitrate filter or does the effect on Kh
become less severe as the flow rate through the denotrator is increased?

rgds

Iain

[Kveill]

Richard

Thanks for the help. I was thinking of using clear tubing in a clear acrylic
pipe (if I could find one, if not I was going to use PVC pipe). Why do you
suggest that I do not use clear tubing?

I was also thinking of using siphon from the main tank to into the coil
denitrator instead of a pump. Do you think this will be too much or too
little flow? I also have a Mini*Jet pump that pumps 13-100 gph is currently
sitting in a box. Will that be too much of a water flow?


"richard reynolds" > wrote in message
.. .
> Kveill > wrote in message
> ...
> > I have been looking at different DIY plan for Coil Denitrators and I was
> > wondering if anyone has had any luck building one of these things. I am
> > really curious what kind of pump and flow rate did you use. Can anyone
make
> > any recomendations or give me specific directions on how to build one?
Any
> > information will be apprecitated.
>
> ive built a few, ive made a few. ive never really had a seperate pump,
ive always used a
> return/canister/gravity into sump/T off a powerhead the volume is low,
the pressure is
> even lower no real need for a pump
>
> > From what I have heard you should get a some PVC pipe 3-4" diameter and
run
> > 75-100ft of 1/4in clear tubing around and fill the middle of the tube
with
> > bio-balls. Then you should let the output drip at 1 drop/sec until the
unit
> > has cycled then you can open it up to flow at full speed once the unit
has
> > cycled. I have heard of cycle time between 6-8 weeks. Does this sound
about
> > right? Thanks
>
> there are a zillion things you can do with the coil, how you wrap it,
where you put it,
> how you put it, none of it really matters except keep it dark and un
kinked, i suggest NOT
> using clear tubing, unless you place all of the clear tubing inside
something that is
> dark. 6 weeks is about the time frame for cycling, ill agree with 8 but
it seems longer
> than ive ever had to wait. while it cycles it will produce some nitrite,
not enough to
> worry you, but use it for a test to see how far along in its cycle you
are, nitrite == not
> done, nitrate it just depends on how much is going into the unit, it
should consume more
> than 1/2 the nitrate level of what goes in. but it doesnt do so good at
getting 0 on low
> nitrate range kits
> expect the output to have low ph, its not perminent and only requires gas
exchange to
> bring the ph back up to what the tank level is. another thing full speed
shouldnt be
> forceful if it is it will disrupt the bacteria, it normally lives in low
water movement
> areas.
>
>
> --
> richard reynolds
>
>
>
>

[Iain Miller]

>
> I cant totally help you only guess, I KNOW that the CO2 in the coil
denitrifer is
> increased and O2 is decreased and Kh is un-effected IF the one you have
doesnt do the same
> thing, then thats different. in a coil system bacteria consume oxygen
while its in the
> coil before it reaches the bio balls, where other bacteria consume nitrate
and something
> else (comeon chemistry experts tell us how its done :) )

Same bacteria, my filter is just stuffed with pure Sulphur (supposedly to
feed the bacteria). Interestingly enough the cannister is clear and the
instructions make no mention of keeping it in the dark - in fact the only
thing they say is that it must be upright - they suggest you mount it on a
wall! Mine is in fact mounted inside the cabinet under my tank so it is
basically dark in there.

How did you test for the increased CO2? If it is happening like that I
wonder where the carbon is coming from?

If you have assumed that the CO2 is up because the Ph is down then I'm not
sure that's what's going on. I tested the Kh of the water coming out my
de-nitrator and it is markedly lower than the Kh of the water in the tank.
That would have a side effect of lowering Ph as well (without needing an
increased CO2 level to do it).

rgds

Iain

[richard reynolds]

Iain Miller > wrote in message
...
>
> >
> > I cant totally help you only guess, I KNOW that the CO2 in the coil
> denitrifer is
> > increased and O2 is decreased and Kh is un-effected IF the one you have
> doesnt do the same
> > thing, then thats different. in a coil system bacteria consume oxygen
> while its in the
> > coil before it reaches the bio balls, where other bacteria consume nitrate
> and something
> > else (comeon chemistry experts tell us how its done :) )
>
> Same bacteria, my filter is just stuffed with pure Sulphur (supposedly to
> feed the bacteria). Interestingly enough the cannister is clear and the
> instructions make no mention of keeping it in the dark - in fact the only
> thing they say is that it must be upright - they suggest you mount it on a
> wall! Mine is in fact mounted inside the cabinet under my tank so it is
> basically dark in there.

for you it might not matter, if all that bacteria is stuffed in some hole inside a 1mm
chunk of sulphur then the unit in the light or dark wont do any thing.

> How did you test for the increased CO2? If it is happening like that I
> wonder where the carbon is coming from?

you can also measure O2, and know that O2 is consumed which increases CO2

> If you have assumed that the CO2 is up because the Ph is down then I'm not
> sure that's what's going on. I tested the Kh of the water coming out my
> de-nitrator and it is markedly lower than the Kh of the water in the tank.
> That would have a side effect of lowering Ph as well (without needing an
> increased CO2 level to do it).

IF Kh is unchanged and PH is changed then CO2 has changed, did I assume kinda, but only
kinda this is how a coil works, yours i have no idea, i can kinda guess from what your
saying, and maybee something is consumed the sulphur maybee?? along with Kh, or maybee the
sulphur alone will lower Kh

a note on one of your other responses, you want anoxic not anerobic, the difference is one
removes nitrate and the other kills everything in your tank by creating
hydrogensulfate(ide ??? another detail for the chemistry experts) gas. not that it
matters much

> rgds
>
> Iain
--
richard reynolds

[Iain Miller]

>
> you can also measure O2, and know that O2 is consumed which increases CO2
>
> > If you have assumed that the CO2 is up because the Ph is down then I'm
not
> > sure that's what's going on. I tested the Kh of the water coming out my
> > de-nitrator and it is markedly lower than the Kh of the water in the
tank.
> > That would have a side effect of lowering Ph as well (without needing an
> > increased CO2 level to do it).
>
> IF Kh is unchanged and PH is changed then CO2 has changed,

True, but as per my previous post KH is changing in my filter

did I assume kinda, but only
> kinda this is how a coil works, yours i have no idea, i can kinda guess
from what your
> saying, and maybee something is consumed the sulphur maybee?? along with
Kh, or maybee the
> sulphur alone will lower Kh

Not sure but dropping Ph seems to be a generic issue with de-nitrators - I
wonder in fact if that is a mis-nomer & it is a secondary effect of dropping
Kh. If you have a coil running now I'd be interested to know if there is a
variation between the Kh in your tank & that coming out the coil.

rgds

I.

[richard reynolds]

> Not sure but dropping Ph seems to be a generic issue with de-nitrators - I
> wonder in fact if that is a mis-nomer & it is a secondary effect of dropping
> Kh. If you have a coil running now I'd be interested to know if there is a
> variation between the Kh in your tank & that coming out the coil.
>
> rgds
>
> I.

droping co2 is ALWAYS an issue at least in part its how they all work, one could power
there denitrator with an air lift in which the end output would have normal co2, or use a
venturi, output into a skimmer will do it. the list goes on and on, ive been through this
before but just to be certain ill test the Kh of a quasi control tank a 10gallon with
nitrate levels of 200ppm i put an already established coil onto it from another tank. the
Kh was 11dkh its been going sence 16:00pst ill test again at 21:00pst then sometime
tomorrow and post all the #'s btw its a large coil and will circulate the tank water in
aprox 2 hours. I might check it then just to see what the #'s come out as, but wont post
them at that time.

my other tanks that run denitrators full time including a FO(gets no addatives) have had
no KH issues

ps delayed post forgot to hit send :(
--
richard reynolds

[Iain Miller]

>..... but just to be certain ill test the Kh of a quasi control tank a
10gallon with
> nitrate levels of 200ppm i put an already established coil onto it from
another tank. the
> Kh was 11dkh its been going sence 16:00pst ill test again at 21:00pst then
sometime
> tomorrow and post all the #'s btw its a large coil and will circulate the
tank water in
> aprox 2 hours. I might check it then just to see what the #'s come out as,
but wont post
> them at that time.

Any results Richard?

[richard reynolds]

i hozed the test by not testing the water after i added the nitrate, though i did test
before adding and alk was basically unchanged, it seemed to change a tad when there was
nitrate to remove, and not at all when there wasnt its still going and I just tested the
KH its at 10 so its a decrease but its also been running a week with nothing in it:) once
the stuff i am adding for nitrate desolves completely ill test the kh again see if its
changing the alk

--
--
richard reynolds



Iain Miller > wrote in message
...
> >..... but just to be certain ill test the Kh of a quasi control tank a
> 10gallon with
> > nitrate levels of 200ppm i put an already established coil onto it from
> another tank. the
> > Kh was 11dkh its been going sence 16:00pst ill test again at 21:00pst then
> sometime
> > tomorrow and post all the #'s btw its a large coil and will circulate the
> tank water in
> > aprox 2 hours. I might check it then just to see what the #'s come out as,
> but wont post
> > them at that time.
>
> Any results Richard?
>
>

[richard reynolds]

ok 10dkh so a small change but no change with the addition nitrates enough for 200ppm

it would seem to consume them a little (remember 10gallon), but only when its consuming
nitrates. this 10 isnt a cycled tank, it has no source of ammonia/nitrite/nitrate besides
what I added to it. so scaling that up to something usefull with a nitrate source it
probibly does consume alk, and you might expect it to stop as soon as you get to a lower
level in your tank..

--
--
richard reynolds



richard reynolds > wrote in message
. ..
> i hozed the test by not testing the water after i added the nitrate, though i did test
> before adding and alk was basically unchanged, it seemed to change a tad when there was
> nitrate to remove, and not at all when there wasnt its still going and I just tested the
> KH its at 10 so its a decrease but its also been running a week with nothing in it:)
once
> the stuff i am adding for nitrate desolves completely ill test the kh again see if its
> changing the alk
>
> --
> --
> richard reynolds
>
>
>
> Iain Miller > wrote in message
> ...
> > >..... but just to be certain ill test the Kh of a quasi control tank a
> > 10gallon with
> > > nitrate levels of 200ppm i put an already established coil onto it from
> > another tank. the
> > > Kh was 11dkh its been going sence 16:00pst ill test again at 21:00pst then
> > sometime
> > > tomorrow and post all the #'s btw its a large coil and will circulate the
> > tank water in
> > > aprox 2 hours. I might check it then just to see what the #'s come out as,
> > but wont post
> > > them at that time.
> >
> > Any results Richard?
> >
> >
>
>

[Iain Miller]

"richard reynolds" > wrote in message
. ..
> ok 10dkh so a small change but no change with the addition nitrates enough
for 200ppm
>
> it would seem to consume them a little (remember 10gallon), but only when
its consuming
> nitrates. this 10 isnt a cycled tank, it has no source of
ammonia/nitrite/nitrate besides
> what I added to it. so scaling that up to something usefull with a nitrate
source it
> probibly does consume alk, and you might expect it to stop as soon as you
get to a lower
> level in your tank..
>

That makes sense with what I have seen - as my Nitrate levels in the tank
have fallen so the effect on the Kh seems to be less dramatic.
Thanks for doing that - something else learned.

I.