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DIY De-nitrate coil/reactor

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Hi guys,

thought i would share my most recent project

So as some of you are aware I work away from home, 2 weeks on 2 weeks off, So my tank maintenance has to fall within my time off.

On my sumped rack system in the garage (approximately 700lt over 5 tanks) I usually do 30-40% water changes once every 2 weeks, the day i get home, then the day before i leave, This has been going well for the last 6 months or so, however recently i have noticed my nitrates were climbing, at its peak up around 90 - 100ppm, very scary.

After doing lots of small water changes ( 10-20% every 2 days) i have managed to get it back down to 50ppm, still not great but at least its coming down.

After doing a but load of research on water chemistry, and talking to a friend of mine who is into saltwater in a big way, I decided to build my self a De-nitrator.

so as you guys probably know, the nitrogen cycle in a tank is... (and if i explain this incorrectly please let me know)

Fish Waste/ un eaten food --> ammonia --> Nitrites --> Nitrates

the bacteria that breaks down the highly toxic nitrites to nitrates are oxygen dependent, they thrive in wet/dry sumps and filters.

Traditionally you can remove Nitrates from your water through water changes, and plants will use them to an extent.

There is another step that can become apparent in some filters and thats the presence of anaerobic bacteria that will break down the Nitrates back into Nitrogen gas.

This bacteria thrives in low oxygen, low flow environments. Something a Denitrator does perfectly.

So i have built a basic unit, Pics and plans attached,

Parts list,

1 x slow flow powerhead ( I've used a 350lt/hour at 0.7m head height)

1 x 90mm x 1000mm pvc pipe

2 x 90mm pvc end caps

1 x 19mm x 900mm riser

1 x 19mm threaded bulkhead

1 x roll of gutter guard

1 x 30m of 4mm irrigation pipe

1 x 4mm irrigation tap - to control flow

You will also need appropriate plumbing atachments to get back into the sump. I've used 19mm irrigation fittings because thats what i had laying around

Cut the gutter guard into 1/4s then wrap around the riser in 4 parts, I then wrapped the 4mm tubing around this, starting from the bottom working my way up. Tuck each wind up against the previous one so it is all neat, this allows more tubing to fit.

In my case I was able to get approximately 25m of tubing into the reactor.

So the water is pumped out of my main tank through the 4mm tubing, into the reactor, down the winds of the tubing, then out into the reactor at the bottom. The water then moves up through all the gutter guard, finally flowing back down the riser and out of the bulkhead at the bottom and then back into the sump.

The flow needs to be about 1 drop/second until the bacteria has established.

The science behind it is this. By running the water through the tubing it removes most of the oxygen from the water, this allows a perfect anaerobic environment to thrive at the bottom of the reactor.

I have been keeping a very close eye on my nitrate, nitrite and ph levels since it has been running and have found the following.

Day 1 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 80ppm

Day 1 - Reactor - PH 7.2 - Nitrite 0ppm - Nitrate 80ppm

Day 2 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 60ppm

Day 2 - Reactor - PH 7.2 - Nitrite 0ppm - Nitrate 40ppm

Day 3 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 50ppm

Day 3 - Reactor - PH 6.5 - Nitrite 2ppm - Nitrate 40ppm

Day 4 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 60ppm

Day 4 - Reactor - PH 6.2 - Nitrite 3ppm - Nitrate 30ppm

Day 5 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 50ppm

Day 5 - Reactor - PH 6 - Nitrite 5ppm - Nitrate 10ppm

Day 6 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 50ppm

Day 6 - Reactor - PH 6.8 - Nitrite 3ppm - Nitrate 5ppm


Day 7 - Tank - PH 7.2 - Nitrite 0ppm - Nitrate - 50ppm

Day 7 - Reactor - PH 7.0 - Nitrite 0ppm - Nitrate 0ppm

I did todays test 3 times and couldn't believe it. From what I have read it should have taken at least 2-3 ++ weeks to establish. I even took both my tank water and water from the reactor down to my lfs to double check it. He checked and confirmed the water from the rector was 0ppm nitrates and nitrites.

I Use the API master test kit, Mate at the LFS used his Redsea test kit (both the normal and the low range nitrate tests) all confirmed 0ppm.

I have now upped the flow rate to 2 drops/sec, the plan is to let this run for a few days, closely monitoring ph/nitrite/nitrates, and once nitrites/nitrates seem to be stable the upping it to 3-4 drops/second.

I know this is a bit long winded but I am really happy with the results and wanted to share. Please If you decide to try this yourself monitor your water closely, you do run the risk of a sharp Ph drop, and this could shock/kill your fish.

I also want to re-iterate this is not something that should replace doing water changes, merely something that will help keep the water at its best quality for our fish.

questions?? Comments??

thanks for reading..




Edited by Kremit

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That really cool kermit. But how do you have it setup in your system? it would have to run parallel to the sump wouldnt it? i would think the flow rate would be 2 low otherwise

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yeah,, seperate pump running out of my main growout tank, a 5ft, through the coil then down into the return section on the sump. I have a separate 8000lt/hr pump running my normal filtration

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