Denitrification, carbon, oxygen etc..
- Thread starter Ontheway
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Hey there, yes are some new experiences actually.
Lately, I decided to add a canister filter to sump which will work externally. I was in trouble with some small snails. Their shells were clogging the mesh I installed to inlet of the return pump. There were a black sponge filter and a filter wool layer in the canister, originally, and I decided to keep them for the first run, then remove with the first cleaning. Since the filter box holes are small enough to keep the shells within canister, this level of rough mech. filtering was enough for me. Canister's outlet were in same section with siporax mini-pump. So siporax container was feeding with freshly filtered water (again, sponge and a layer of filter wool).
Long story short, about 2-3 days later, I realised that siporax container started to fail to reach pH 8.x level. Waited a bit more and hand-triggered siporax pump to equalize pH to tank's level. And in the following stage, I become sure that denitrification speed certainly slowed down on siporax side, indicating something going wrong.
Denitrification bacteria needs three main things, nitrat (there are a bit), phosphate (0.06 ppm) and organic carbon. My first guesstimate was lack of organic carbon, due to heavy filtering of fresh filter wool. After observing pH recovery durations in siporax container to have an opinion on mean duration of pH increase, pulled out canister filter and throughly cleaned it, and of course, filter wool sent to trash, but sponge filter remained.
The plan worked surprisingly well and after 3 4 days of patience, pH increase speed within siporax container, healed. I must admit it is still not as fast as before, but can reach 8.1x pH within a day. This was happening in 12 hrs, formerly.
This situation rises a lot of questions in My mind, like, how a heavy mechanical filtering effects ongoing denitrification, in a regular tank...
My next plan is to remove sponge too, to see how it will be effected.
Lately, I decided to add a canister filter to sump which will work externally. I was in trouble with some small snails. Their shells were clogging the mesh I installed to inlet of the return pump. There were a black sponge filter and a filter wool layer in the canister, originally, and I decided to keep them for the first run, then remove with the first cleaning. Since the filter box holes are small enough to keep the shells within canister, this level of rough mech. filtering was enough for me. Canister's outlet were in same section with siporax mini-pump. So siporax container was feeding with freshly filtered water (again, sponge and a layer of filter wool).
Long story short, about 2-3 days later, I realised that siporax container started to fail to reach pH 8.x level. Waited a bit more and hand-triggered siporax pump to equalize pH to tank's level. And in the following stage, I become sure that denitrification speed certainly slowed down on siporax side, indicating something going wrong.
Denitrification bacteria needs three main things, nitrat (there are a bit), phosphate (0.06 ppm) and organic carbon. My first guesstimate was lack of organic carbon, due to heavy filtering of fresh filter wool. After observing pH recovery durations in siporax container to have an opinion on mean duration of pH increase, pulled out canister filter and throughly cleaned it, and of course, filter wool sent to trash, but sponge filter remained.
The plan worked surprisingly well and after 3 4 days of patience, pH increase speed within siporax container, healed. I must admit it is still not as fast as before, but can reach 8.1x pH within a day. This was happening in 12 hrs, formerly.
This situation rises a lot of questions in My mind, like, how a heavy mechanical filtering effects ongoing denitrification, in a regular tank...
My next plan is to remove sponge too, to see how it will be effected.
Randy Holmes-Farley
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If you have nitrate, it is replacing the alk that the nitrification process took away when ammonia became nitrate. If nitrate runs out, no more alk boost. 
Certainly. Ph (alk) boost coming from denitrification process. And nitrate is currently around 2 ppm, as in last two months. So denitrification should still continue in same speed. Whats slowing it down, suddenly?If you have nitrate, it is replacing the alk that the nitrification process took away when ammonia became nitrate. If nitrate runs out, no more alk boost.
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What do you mean slowing it down suddenly? Is nitrate the same as before?
Yes it is same. No serious change. Fluctuates between 2 and 5 ppm (max).
Sudden means; 12 hr periodic ph rise in siporax container suddenly extended to 2-3 days or more, to reach same ph level... (After canister filter)
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The amount of organic matter in the water is also a factor, since denitrification requires it. And a change from 2 to 5 ppm means a 2.5x change in available nitrate, so it might take 2.5 times as long, or more, if organics begin to run out.
Thanks Randy that's right. May I ask your opinions about effects of fine mechanical filtering (filter wool, sock, etc.) on availability of organic carbon to denitrification? Are there any tests or other type of evidence showing possible effects?
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Mechanical filtering takes out particulates, but I think mostly soluble organics are used for denitrification, although particulates may be sources of dissolved organics as they break down.
The difference in denitrification speed in siporaxes after filter wool addition, and after removal of filter wool was day and night to me. Although there may be some others reasons, like utilization of materials, around filter wool, due to microbiology activity...Of course not sure what may happen in a week, in the filter wool.
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Sorry, I cannot tell if you mean it went faster or slower with particulate filtration?
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HI,
I have a 160G-650lt net volume skimmerless mixed reef, set it up nearly over a year, with RDSB, ATS and chaeto keeping down the nutrients. i run also 350ml carbon in a canister filter and 150ml GFO in a reactor. with the above filtration i used to have no3-0 salifert and po4 0-0.03 hanna736. i can not measure DOC or POM , the water i change is not tinted yellow, but i wanted to increase the denitrifying bacteria population, to consume any excess organics i might have. so since january i install a DIY open top reactor with 7lt of seachem denitrat, with 450lt/h flow through a filter with only a sponge ,bottom to top. since january i also nearly double fish population and feeding , also i started adding daily rotifers and phytoplakton, produced by myself. so since february i measure 5-8ppm no3 which was my target, and po4 remain 0-03. But i have't any indication that denitrification started in the reactor! i measured no3 and Kh , at the reactor output, and was always similar values to DT! so since april i reduced the flow to 300lt/h, and mid june even more to 150lt/h, again with no measurable indication that denitrification is happening in the reactor!
Do you think that the population of denitrifying bacteria in the media of reactor, is to small to get any measurable proof that are really there? Is it possible, that media in the reactor, house only nitrifying bacteria? I am considering to put the small filter supplying flow in the reactor, on a timer, but i am afraid, the stagnant water in the reactor. Do you thing the last one, a good idea to increase the dentrifying bacteria population?
Thanks in advance, for any help.
I have a 160G-650lt net volume skimmerless mixed reef, set it up nearly over a year, with RDSB, ATS and chaeto keeping down the nutrients. i run also 350ml carbon in a canister filter and 150ml GFO in a reactor. with the above filtration i used to have no3-0 salifert and po4 0-0.03 hanna736. i can not measure DOC or POM , the water i change is not tinted yellow, but i wanted to increase the denitrifying bacteria population, to consume any excess organics i might have. so since january i install a DIY open top reactor with 7lt of seachem denitrat, with 450lt/h flow through a filter with only a sponge ,bottom to top. since january i also nearly double fish population and feeding , also i started adding daily rotifers and phytoplakton, produced by myself. so since february i measure 5-8ppm no3 which was my target, and po4 remain 0-03. But i have't any indication that denitrification started in the reactor! i measured no3 and Kh , at the reactor output, and was always similar values to DT! so since april i reduced the flow to 300lt/h, and mid june even more to 150lt/h, again with no measurable indication that denitrification is happening in the reactor!
Do you think that the population of denitrifying bacteria in the media of reactor, is to small to get any measurable proof that are really there? Is it possible, that media in the reactor, house only nitrifying bacteria? I am considering to put the small filter supplying flow in the reactor, on a timer, but i am afraid, the stagnant water in the reactor. Do you thing the last one, a good idea to increase the dentrifying bacteria population?
Thanks in advance, for any help.
Randy Holmes-Farley
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IMO, the flow is too high to see much drop from entry to exit, but that does not mean it isn't working.
I agree, but you may still apply a small test. Stop Reactor flow for12 hours and after this period, test kh of both DT and reactor water. If still same or close to each other, add another 12 h, test and report back (dont forget to re run the reactor, after 24h max). If you already have a nitrite test, you can try it with tests above..
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FWIW, I doubt any nitrate kits can detect a 10% change in nitrate, and yet in the above situation where flow is nearly 1 tank volume per h, if it really did drop 10% with each pass, the tank nitrate would drop something like 90% per day, which obviously is not what folks get.
IMO, the flow is too high to see much drop from entry to exit, but that does not mean it isn't working.
Thank you both of you. Randy ,even if I manage to confuse you with litres, flow currently is 150lt/h ,in 650lt net volume[emoji6] ,you are absolutely right, it is now very clearly to me, that there's no way to measure with the current setup, different values of No3 or Kh at the reactor outlet.FWIW, I doubt any nitrate kits can detect a 10% change in nitrate, and yet in the above situation where flow is nearly 1 tank volume per h, if it really did drop 10% with each pass, the tank nitrate would drop something like 90% per day, which obviously is not what folks get.
And Ontheway thanks for the idea , to obtain evidence of denitrification , but 12h aren't to much time, for the water to be stagnant in the reactor? I red that you achieve the best results in this way, but again I am worried for such a long time to stop the flow in the reactor....
What do you both thing, of putting the filter supplying water to the reactor, on timer, and run it , e.g. for 10min per hour? In this way won't I boost the population of denitrification bacteria in the reactor?
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Hi, 12 hours or even 24 h is not too much, as long as young keep the Lid open. The only concern may be inside of the reactor hoses. If you have longer hoses some bad smell may develop, still no big deal in 650 liters.
You May decide how long you can keep reactor stagnant and then measure kh again then compare to initial. The test I offered above is not nitrate but nitrite, rises of it is common during initialization of denitrifying bacteria.
A side note about seachem denitrite, it requires slower flow then another similar product, seachem matrix. I made a test with seachem denit and applied a really slow flow (down to drops) there were high nitrates in water (around 40) and denitrification started right after that high nitrite started to flow into tank. From experiences, If you want to use a denitrator, and have nitrates above 20, it s best to lower it down to 15-20 ppm first, with water changes.
