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sharknado

small canister as a nitrate reactor ?

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Ok long story short, I have a 200l malawi tank that's been established for a long time but recently noticed that my nitrates are through the roof (80) This despite:

- twice daily vaccuming of all the solid waste using an eheim quickvac (all the poop ..collects in one deadspot for easy removal)

- weekly wc of between 30-50%

- monthly canister clean

It's an Aquis 1250 s2 canister with plenty of media and sponges but it's a nitrate factory. Now my research leads me to believe that I probably have very little if any anaerobic bacteria (the kind that consumes nitrates and lives in oxygen-free/deprived environment) because the flow of my canister is about 600lph (it's rated at 1400lph but I measured the real output). For example, Seachem claim their De-Nitrate (miniature version of the matrix bio media) is excellent for anaerobic bacteria as long as the flow is < 200 lph. So obviously not gonna work with my main canister.

So the plan, so far, is to install a 2nd small inexpensive canister such as the Ocellaris 400 (about $40 on special), fill it up with the bio media and restrict the flow using a valve or perhaps just excessive floss material until it flows < 200lph or preferrably 50-100lph. That should be the ideal environment for anaerobic bacteria.

 

Can anyone spot any flaws in my plan ? The only thing that worries me (a little) is restricting the flow sufficiently .. Like I said I'd like it to be under 100lph, preferrably 50 or so. Just enough so it's not completely stagnant and a hydrogen sulfide bomb

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I’ve seen overseas threads do this with homemade ‘canister’ filters and from memory success. Cant remember how much nitrates drop.

This would be more US or UK farms but just in case, I assume no nitrates in tap water used for tank water changes??

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restricting flow may put pressure on the motor. i would think it'll be better to get a broken and not leaking cannister as your media container and getting a small motor to run water through it. i have done it before - tank intake to dummy cannister and a small motor inside the tank to draw water. this lessens burden on the motor as well as gravity helps with circulation.

alternatively, there are some filters that you can adjust flow but not sure how low they go.

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I think the whole putting ressure on motors by restricting flow might be a bit of a myth and/or does not apply to these erlectro magnetic motos with magnetic impellers ..from what I've read in a few places anyway, thats why most canister have built in valve to restrict flow

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my concern has switched to the byproduct(s) of the anaerobic process ie hydrogen sulfide ...need to research just how much of an issue this would be with SOME constant flow

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As you say sharknado, restricting flow won't increase the load on your motor in filters with a magnetic impeller.   Problem with restricting flow to the levels you need is that you will likely get overheating of the motor as canisters rely on water flow for cooling.

A couple of points - I'm guessing from what you describe that you are testing using an API test kit.  Can I suggest that before you do anything else, that you test your water using another brand of kit - preferably one that uses a powder as one of the reagents.  We see far too many people chasing "high nitrates" where the only problem they have is their brand of test kit. 

If you truly do have a nitrate problem, and you aren't overfeeding or using a "budget" fish food, then can I suggest you consider placing one of the large blocks of Marine Pure in a low flow area of your tank - perhaps hidden under rock-work.  I have some in low-flow sections of a couple of sumps and have had appreciable reduction in nitrates using them.  It will take months for the bacteria to establish, so you need to be patient.

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The canister I was eyeing for this was the Sunsun 603b which has the pump mounted on the outside and it's only <4W from what I recall so I don't think overheating will be an issue. 50-100lph flow isn't nothing either ..thats still a fair amount of water/cooling I reckon

Yes it's an API test kit - can you recommend another brand ? I've tested my mates tank with this same kit and the result was < 10ppm and he uses an UGF and NEVER vaccums. Tested my tap water (0ppm) too so I dont think it my kit thats just showing high nitrates all the time but it would be cool to try a different brand especially if the process is faster and/or easier ie. doesnt require all the shaking..

I'm using NLS AlgaeMax and feed twice a day what they can eat in under 1min without any of the stuff falling to ground etc

I've just stuffed 3l of Seachem Pond Matrix in my main canister hoping the much larger rocks will allow for anaerobic bacteria to survive deeper inside the rocks

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