Nitrate reactor

[ryang85]

This is my first post so I figured I'd share something useful . There's not a lot of information available on nitrate reactors for FW but luckily they are heavily used in SW tanks so most of the concepts can be used.This was for a 75 gal mixed peacock cichlid tank I was constantly trying to keep nitrates below 40ppm with bi weekly water changes .
After some extensive research I built this ugly thing which is a simple design, a 6 foot tall 2" pipe that can be slowly and constantly recirculating and bleed out water slowly. In order to do this I split off the output of my own DIY 650gph canister filter with 1.5 gallons of matrix.( I can post more about that if anyone wants to see how that works) I figured the oxygen breathing bacteria in the main canisters would help deplete some 02. Then I ran 150 foot of small 1/4in irrigation hose I picked up at home depot for 10 dollars. I left it in the prepackaged coil so it fits nicely out of the way. I figured this would remove most of the 02. Then had a T with one side of the re-circ and the other side going to the pump, the pump which I used a 12v dimmer switch to control fed directly to the 2" pipe which was filled with a gallon of seachem denitrate. Ive had it running for about 3 months set up on a auto doser with two 4ml vodka dosings daily. Currently my tank nitrates stay below 10ppm and generally are under 5 ppm if I dont feed aggressively. I have the reactor treating roughly 22 gal per day with output at 0ppm.


Now for my 180 gallon predator hap tank I'm starting to think up a reactor on a larger scale, my plan is to build 2 five foot long chambers out of 2.5'' pipe. I want to make it sit horizontal so I can mount it above my sump and underneath my tank, Im worried about trapping gas bubbles with the horizontal design so I will need to figure that one out. I will post some more info as I piece it together.

 

[BIG-G]

Interesting, The vodka dose I assume is to add a carbon source for the nitrifying bacteria.
Is that dosed directly into the tank or into the nitrate reactor?

I experimented with vodka dosing when I had a reef tank.
It was my understanding of the idea with saltwater was to give bacteria growth a boost with a carbon source in turn allowing the protein skimming to be more effective in removing phosphate and nitrite waste thru the additional bacteria growth before it could be totally converted to nitrate thus lowering nitrate in the system.
I understand that nitrate being broken down in this case is done through an anaerobic process.
Would the carbon dosing be necessary or does it just act as a boost of sorts?

 

[islandguy11]

Great first post, thanks for sharing and look forward to more updates/pix.

I'd also be interested to know if the carbon dosing is necessary.

 

[kno4te]

Please share more of the details.

 

[ryang85]

In terms of the carbon dosing, from my research it is necessary in some form since the anaerobic bacteria feed off of carbon and rip apart nitrate molecules only to get the oxygen molecules( its there form of breathing) . Which is why they can also rip apart certain compounds containing sulfur to make sulfur hydroxide if they run out of nitrates.
Some people have reported large amounts of driftwood helps. Vodka is cheap and easy though especially if you kick out the extra 50 bucks for an auto doser. I got a 2 liter bottle for 20 bucks, the stuff smells and probably taste like gasoline but the bacteria arnt picky about their vodka.
When I first started the reactor I seeded it using seachem stability since they claim that there is anarebic bacteria in the bottle. The reactor cycled in 4 days then worked extremely well for the first 12 days . I could run 22 to 25 gallons per day and have zero ppm output. After that the nitrate output starting going into swings where one day it would work and the next it wouldn't so I slowly started carbon dosing. I dont know if the seachem bacteria were just temporary and died off or that they consumed all of the available carbon sources that may have been in the tank water. If someone has a South American tank with a lot of driftwood and general plant matter Im very curious to see if that would need to be dosed in a smaller amount.
I personally found that the reactor had immediate improved results on carbon dosing. So ive stuck with it.
Another thing i have learned is that over dosing the reactor causes a mess. I can get my nitrates down to zero if i wanted to but the tank starts to fill up with this nasty clear slime that makes a mess of all of the canister filters and effects the water clarity. I assume this happens when carbon escapes the filter before being consumed by the nitrate eating bacteria. To answer the question about dosing directly to the tank you want to absolutely avoid any vodka in your tankwater. I dose right into the re-circulation pump. I can post more pictures when i get back home since i have made a few changes since i took those pictures. As mentioned in a SW tank your protein skimmer will remove that nasty slime and therefor removing all of the nitrates ans phosphates that it consumed, in FW we dont have that option so a exact amount of dosing is critical otherwise its a mess. I have noticed that if over dose for a few days i can skip a few days on dosing and the bacteria will feed on the carbon in the slime. So other than having to clean filters daily the mess will solve itself pretty quickly.
I also learned that less waterflow is better. I actually have been running my reactor on 14gal/day lately and its reducing the filter slime to hardly anything but it does give off a slight sulfur smell from sulfur hydroxide being produced. Small amounts sulfur hyrdoxide isnt that bad in FW tanks because we can run high oxygen levels which detoxifies it immediately, so as a backup measure I keep a ton of surface agitation. That being said if i were to dump a large amount of water from the reactor or let the reactor stand still for many hours it could become toxic so I drain the first gallon into a bucket if i need to stop the pump for an extended period of time. But as long as you have it dialed in there isnt much too worry about other than a slightly smelly fish tank. This is also a result of over dosing carbon so cutting back helps prevent the smell but lowers the nitrate reduction. My tank is extremely over stocked so its been a balancing act to find the proper flow and vodka dose but the last 2 weeks have seem to fallen right into the sweet spot with 14gal/day and 4ml vodka every 12 hours. Once some fish get moved into the 180 i think i will be able to cut back on the dosing. With my bigger reactor i would like to run closer 30gal/day so it would be equivalent to a 100% waterchange in the 180 gal tank and roughly 30 gal sump per week.

 

[johnnymax]

I would love to be able to get away from water changes, but I am not sure I understand enough about this to venture into nitrate removal.....
Thanks for the great post! You have me researching this now.

 

[BIG-G]

In terms of the carbon dosing, from my research it is necessary in some form since the anaerobic bacteria feed off of carbon and rip apart nitrate molecules only to get the oxygen molecules( its there form of breathing) . Which is why they can also rip apart certain compounds containing sulfur to make sulfur hydroxide if they run out of nitrates.
Some people have reported large amounts of driftwood helps. Vodka is cheap and easy though especially if you kick out the extra 50 bucks for an auto doser. I got a 2 liter bottle for 20 bucks, the stuff smells and probably taste like gasoline but the bacteria arnt picky about their vodka.
When I first started the reactor I seeded it using seachem stability since they claim that there is anarebic bacteria in the bottle. The reactor cycled in 4 days then worked extremely well for the first 12 days . I could run 22 to 25 gallons per day and have zero ppm output. After that the nitrate output starting going into swings where one day it would work and the next it wouldn't so I slowly started carbon dosing. I dont know if the seachem bacteria were just temporary and died off or that they consumed all of the available carbon sources that may have been in the tank water. If someone has a South American tank with a lot of driftwood and general plant matter Im very curious to see if that would need to be dosed in a smaller amount.
I personally found that the reactor had immediate improved results on carbon dosing. So ive stuck with it.
Another thing i have learned is that over dosing the reactor causes a mess. I can get my nitrates down to zero if i wanted to but the tank starts to fill up with this nasty clear slime that makes a mess of all of the canister filters and effects the water clarity. I assume this happens when carbon escapes the filter before being consumed by the nitrate eating bacteria. To answer the question about dosing directly to the tank you want to absolutely avoid any vodka in your tankwater. I dose right into the re-circulation pump. I can post more pictures when i get back home since i have made a few changes since i took those pictures. As mentioned in a SW tank your protein skimmer will remove that nasty slime and therefor removing all of the nitrates ans phosphates that it consumed, in FW we dont have that option so a exact amount of dosing is critical otherwise its a mess. I have noticed that if over dose for a few days i can skip a few days on dosing and the bacteria will feed on the carbon in the slime. So other than having to clean filters daily the mess will solve itself pretty quickly.
I also learned that less waterflow is better. I actually have been running my reactor on 14gal/day lately and its reducing the filter slime to hardly anything but it does give off a slight sulfur smell from sulfur hydroxide being produced. Small amounts sulfur hyrdoxide isnt that bad in FW tanks because we can run high oxygen levels which detoxifies it immediately, so as a backup measure I keep a ton of surface agitation. That being said if i were to dump a large amount of water from the reactor or let the reactor stand still for many hours it could become toxic so I drain the first gallon into a bucket if i need to stop the pump for an extended period of time. But as long as you have it dialed in there isnt much too worry about other than a slightly smelly fish tank. This is also a result of over dosing carbon so cutting back helps prevent the smell but lowers the nitrate reduction. My tank is extremely over stocked so its been a balancing act to find the proper flow and vodka dose but the last 2 weeks have seem to fallen right into the sweet spot with 14gal/day and 4ml vodka every 12 hours. Once some fish get moved into the 180 i think i will be able to cut back on the dosing. With my bigger reactor i would like to run closer 30gal/day so it would be equivalent to a 100% waterchange in the 180 gal tank and roughly 30 gal sump per week.

Thanks for the clarification on the dosing.
This makes perfect sense and fits with my experience using vodka for a carbon source in my reefing days.
I use to buy the cheapest vodka I could find.
It seemed like no one would want to drink it anyway lol.
I’ve read that you can use sugar as a carbon source as well but I never experimented with it.
It seems less accurate and more messy than necessary.
Did you have a base starting point for the amount or did you start with small amount and ramp up the dosing?
How did you arrive at 4ml ?
What was your starting dose?

 

[ryang85]

I actually looked at the aquripure reactor user manual for the original dosing. It was 12ml every 3 days I think. Then i noticed that the output would start to have higher nitrates after a day so I changed it to daily. Then twice a day. I tried 3 times per day but ended up with slime. And after a lot of nitrate test I ended up at 4ml. At 5ml twice per day I can really drop my nitrates in a hurry but I have to clean the filters daily to prevent slime.

 

[BIG-G]

This is something that has interested me for a while.
I’ve done a lot of research but haven’t pulled the trigger on it yet.
Thanks for posting.
Keep us updated on how it works long term.

 

[ryang85]

So I got my canisters build, I used 3" abs in 5' long sections and a mix match of pvc fittings I had laying around the shop, for me its all scrap material. The total length with fittings is right under 6 feet so it will fit above my sump in the cabinet. It is the exact same concept as my first once except on a bigger scale and cut in half in terms of length.

The inlet from the pump will be a .5" hose and the recirculation outlet back to the pump is the same. The little brass hose barb with the needle valve is for outlet effluent back to the tank. If anyone wants more details or has questions feel free to ask. I would like to see others taking advantage of these systems.