Progress in My Aquarium Engineering Sulfur Denitrifier

justonwo · Sep 9, 2016

I started another thread about the Korallin denitrator but ultimately decided to go with the Aquarium Engineering product, thanks to the recommendation from another forumite. I decided to start a new thread since the title of the old thread isn't really applicable anymore.

I'm on day 2 of the 4" sulfur denitrifier. I started with about 20 ppm nitrate, a number that I've never really been able to get below, despite many different approaches over several months. I am starting to see about 0.25 ppm nitrite (with an "i") in the denitrifier effluent, which I take to be an indication that the new sulfur reactor is cycling. I will monitor the progress with my nitrates in this thread.

The overall quality of the unit is unimpeachable. Everything arrived neatly packed. The recirculation pump is DEAD quiet. I can only detect that it's running by putting my hand on it. The hardest part of the installation was finding a 1/2" OD tee for my GFO pump!

justonwo · Sep 12, 2016

Guys, I had the flow set to about 4 drops per second for the first 5 days, and I'm seeing 0.25 ppm nitrite in the effluent and no drop in nitrates. I'm decreasing the flow rate to 1 drop per second. For those of you that have commissioned a sulfur denitrator, do you wait until the nitrite is undetectable before you even begin testing nitrate?

revhtree · Sep 13, 2016

Nice reactor!

justonwo · Sep 14, 2016

Thanks! I've got the flow rate now at 1 drop per second, maybe slightly slower. My nitrites are currently 5 ppm+ based on the API test kit (the only nitrite kit I have). Looks like things are really cycling. It will be interesting to see how quickly nitrite drops and then, of course, nitrate after it. I'll keep you all posted.

justonwo · Sep 15, 2016

At 1 drop per second, the nitrites have dropped down to 0 ppm. The nitrates still continue to be tank level. Now that the nitrites seem to be cycled, I expect nitrate to start coming down.

justonwo · Sep 16, 2016

I'm still at 1 drop per second and the nitrates have started to fall. The tank nitrates are about 20 ppm but the effluent from the reactor is about 8 ppm at this point. Hooray, it's working!

justonwo · Sep 17, 2016

Alright, nitrate values have dropped to zero in the effluent. I'm now increasing the flow rate from 1 drop per second to 2 drops per second, or about 10 mL/min. That's about 5% of my water being processed per day.

With a 10 gallon water change per week, I'm able to keep nitrates stable at 20 ppm. That means I'm removing nitrate as quickly as it's being produced or, put another way, any additional nitrate removal should result in an overall drop in my tank nitrate concentration.

So, with the current throughput rate on my reactor of 10 mL/min, I'll be processing 27 gallons per week, which is about 33% of my total tank volume. Therefore, even with this relatively low flow, a not insignificant volume of my tank is processed every week. Based on this rough math, I would expect a 33% drop in nitrate by next weekend - to about 13 ppm. Of course, I'll be increasing the reactor flow 2-3 times this week as the capacity increases (i.e. the bacteria colony builds up), so the total water turnover is likely to exceed the 27 gallon per week number. Perhaps as much as 40 gallons total, with a resulting drop in nitrate of about 50% (to 10 ppm).

At this rate, nitrates should approach 0 ppm in 2-3 weeks.

blacktippr · Sep 17, 2016

Following

justonwo · Sep 21, 2016

The flow rate seems to drop overnight because of the buildup of nitrogen, so it's hard to keep the flow constant at this point. I'm still at about 10 mL/min with 1 ppm nitrate in the effluent of the reactor. I'm waiting for it to drop to zero and the flow to stabilize a bit more before increasing the flow rate.

justonwo · Sep 21, 2016

So we are about half-way through the week since the nitrates from the reactor effluent dropped to zero (or close to zero). My tank nitrates have dropped from 20 ppm to about 16 ppm. And we're about halfway to the predicted 13 ppm nitrates in the tank. Things seem to be working exactly as predicted so far.

justonwo · Sep 22, 2016

Alright, I increased the flow a little too rapidly and effluent nitrates went back up. I set it back to 5 ml/min this morning and it was back to zero nitrates this afternoon. Now, I've increased it to 6 mL/min. I'll hold there for a couple of days and then increase in increments of 10%.

justonwo · Oct 3, 2016

I've been having a difficult time keeping the flow steady. I'll set it to a certain value and, presumably because of the generation of nitrogen bubbles, the flow will become restricted and drop to 0 by the next day. I'm trying to go with a higher flow and let the nitrates drop down since the lower flow rates don't seem to hold steady. A little frustrated . . .

justonwo · Oct 13, 2016

Well, I've been at it about a month, and I'm still in start up mode. I've found that I can get 0 ppm nitrate in the reactor effluent with a flow rate of about 100 drops per minute. However, if I leave the reactor over the weekend (as I usually do since my tank is in my office), I will come in Monday morning to find the flow has reduced to almost the point of no flow. So I spend the week trying to get the flow back up with low nitrates in the effluent.

I have also tried to start at a higher flow and let nitrates come down, but that doesn't seem to happen. So I feel like I'm chasing my tail a bit. I will keep at it, but startup is not as easy as I thought it would be.