New Biodenitrator

[Pansy-Paws]

I would argue that this is the only way to go for nitrate reduction on large systems. I initially went with two Phosban reactors to test the concept for myself, before committing to a larger unit

Seeing the test reading of zero nitrates out of the reactor was like magic after struggling with nitrates for a year (we overfeed and that's not going to change ... so we know the source). Doing religious weekly 50 gallon water changes for 2 months steady still only took nitrates from 40 ppm down to 30 ppm, and skipping one week would put us back to the start.

With a DIY reactor based on the Phosban design (two 6" x 36" cylinders), we took the nitrates to zero in 4 weeks on our 500 gallon FO system.

The rotten egg smell can create the occassional "Annacis Island" as my wife calls it, but can be masked with some burning oils until the flow rate is corrected (too low of a flow rate creates H2S). For those who've driven over the Alex Fraser bridge on a muggy summer day, you will understand the reference to Annacis Island

[Delphinus]

Holey mondo reactor size though! Is there any good reading as to how to size a reactor effectively against a total system volume? Or is it mostly guesswork?

Also is there any mechanism to determine an optimal flowrate through the reactor? How long does it take for the smell to go away after adjusting, if indeed you start off too slow? What kind of flowrate do you have on your reactor?

[Psyire]

From what I know, flow rates depend on bioload. It is slightly different for everyone. The .pdf file for the Midwest unit explains how to set your drip rates. (they also cover how to find the optimal flow)

Thanks for the input Lyle, now I really want one. lol

[Pansy-Paws]

Delbeek and Sprung Volume 3 suggests that the volume of sulphur beads be 1% of the water volume. This book was absolutely the best source for information as I was researching and setting up my reactor.

I have 4 gallons of beads for a 500 gallon system, so a little under 1%. To start off, the flow rate needs to be extremely slow (this is very tricky unless you have a nice system like reeferaddict with fine controls - if Korallin had a much larger unit I would have seriously considered that). The drip rate for starting is in the range of 1 drop per second per half gallon of sulphur - that's tough to regulate in a DIY design!

Once cycled (mine took about a week), flow can be increased to around 1 gallon per hour per gallon of sulphur. The flow range seems to be quite forgiving, unless you can't get the flow fast enough due to constricted tubing ... hence my Annacis Island situation. As the nitrates dropped, I found I needed to increase the flow rate into the 8-10 gallon per hour range. I upgraded to a Mag 7, and still needed to redesign the plumbing with 3/4 inch PVC to get the necessary flow.

The smell can last 2-4 hours before the increased flow gets the H2S under control. It can seem like a long time when you have the rest of the family staring you down