Filtration Vs. NITRATES

[lester.elkins]

I have a 75 Gallon undrilled tank that's been running for 6 months. Since cycling the tank I've had a steady rise of nitrates. I do weekly 10% Water changes. Normally after WC nitrate reads 20ppm after a week 40ppm.

I have 70 pounds of live rock which has an open flow design. Fish load is low. 2 small clowns, watchman goby, dotty back, and a blenny. All on the small side. I'm running a eshopps 100 gallon HOB skimmer which gets good dark skimate. I also have a 350 gph canister filter and a HOB Aquatech filter with dual filter pads. Running two 500 gph powerheads and one 1200 gph powerhead, all three are on a wave maker.

I break down and clean the canister filter weekly replacing the filter media pads. I also run BRS ROX carbon and two weeks ago I added a Purgen 100 gallon rated bag to the canister filter and added another Purgen bag to the HOB filter a week later.

I started dosing NOPOX 4 weeks ago with little to no results. I did miss a week while away on business.

I'm preparing to do a 50% WC this weekend to try to lower the nitrates and l'm thinking about not running the canister filter afterwards. I've read a lot of comments about canister filters being nitrate factory's. Do you think just running a skimmer and the HOB filter would be enough? Any suggestions on improvements? I don't really want to do a HOB overflow with sump.

Thank in advance.

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[gone fishin]

I would certainly give it a try removing the canister filter to see what happens.

One thing I would also mention sometimes newer folks tend to overfeed, I think this was one of the hardest thing for me to get a feel for.

 

[mcgyvr]

Take all filters offline and find out..

You don't need them.. Skimmer and water changes should be sufficient..

carbon dosing can take some time too..

 

[lester.elkins]

For feeding I've been measuring an 1/8 of a teaspoon of pellets daily basis. and target feeding a cube of Mysis twice a week to the corals.

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[Michael Hoaster]

Are you starting with nitrate-free water? A lot of city tap water has nitrate. RO-DI fixes that. Hard to tell, but your sand bed looks rather coarse. Fine grain, deep sand beds can process nitrate into nitrogen gas. Macro algae also suck up nitrates.

 

[lester.elkins]

I have BRS RODI system 5 stage and get 0 TDS readings. I'm using Red Sea coral pro salt.

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[rucnnefish]

Your tank looks very clean to me. Where are you at on PO4? Looks like your tank is phosphate limited, and therefore the denitrifying bacteria can't convert the nitrates to nitrogen.

I use a canister filter (Marineland C360) filled with nearly 8L of Matrix, this plus the addition of Prodibio BioClean added every 2 weeks after I rinse the matrix (in old tank water) and you will turn that "nitrate factory" into a highly efficient biological filter. Just remember to feed foods high in phosphates like Reefroids.

 

[BarIzoN]

Hi Lester!

Man, let me tell you something: I also have an undrilled sumpless 55g tank.

I started with two HOB Penguin 150 and no skimmer.

At early beginning, all parameters were well, tank cycled as expected and everything was fine.

After a few months, I saw a nitratre growth. I didn't clear the filters as much as you, but my nitrates were by 20's and 40's.

I have really low bioload with couple litle clowns, a Diamond Goby, a Coral Beauty and one Green Chromis.

Well, I bought an HOB skimmer and I thought that would be the solution for my nitrates. I was wrong.

I decided then to shut off the filters and leave only the skimmer.

Nitrates almost ZERO now.

My 2 cents!



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[BarIzoN]

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[CStrickland]

I think your tank looks great, I wouldn't worry too much about the nitrates.
But if you're curious the easiest thing would be to do a larger water change this week (25% won't be too disruptive if you match temp and salinity) and when you clean the filter pads just don't put them back in the canister. You can run it empty no problem. Then see where you're at next week. I'd be careful about starting and stopping carbon dosing. You can wind up with cyano issues and bacteria blooms sometimes.

Basically I'd say your tanks not broken so don't fix it. Adding purigen, dosing, etc. can all help but you're better off giving each change like a month to take effect than throwing a lot of stuff at the wall to see what sticks.

I would be very surprised if your tank were phos-limited at 6 months without using gfo.

 

[BarIzoN]

Other point here: Don't do the 50% water change.

Shut off the filters, do your regular 20% this week and repeat for the next couple weeks.

Give time to time. Don't try to accelerate the "detox" process.

I can tell you, your livestock is already on high nitrates and it's better for them to slowly detox from that nitrate. It will be better for h you also, by doing only the regular stuff with peace of mind.

- BarIzoN -

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[MiataRacer]

I actually had a really similar problem for a few months after I started my 40B sumpless reef tank as a FOWLR system. My nitrates consistently read between 20-40 ppm, most of the time closer to the 40 ppm side. I found a couple solutions to the problem:

1. I upgraded my skimmer. My CPR Bak-Pak 2R was awful, it didn't skim well for a couple months until I did the airstone mod, which only worked for a couple weeks and then the skimmer was just circulating water again. I now have an AquaC Remora Pro with a Mag 5 pump and the pre-skimmer box and it works much better. I have no other filters on my tank.
2. I started dosing NoPox. I was doing 25% water changes every week with little to no success in reducing nitrates. Now that I dose NoPox, I regularly get readings of 10 ppm, which is fine for me because I only have a candy cane, 3 zoas and a mushroom (plus a dying xenia). And that's with water changes down to 10% weekly. At one point I even got the nitrates down to 5 ppm.

Oh, and one more thing, do you keep detritus cleaned off your rocks? That can also cause nitrates. I didn't until my tank was a few months old, and I couldn't believe what came out of my rocks when I used a turkey baster!

I think like everyone else said, try taking the rest of your filters down and see what happens. Hope this helps!

 

[Timfish]

For what it's worth I never a canister filter that didn't get a leaky O-ring sooner or later and would never recommend using them. And you don't need a skimmer in my experience either. Beside the filter section of Delbeek and Sprungs "The Reef Aquarium" Vol III I would also recommend Forest Rohwer's "Coral Reefs in the Microbial Seas" to get a better idea of how nutrients and DOC affect the microbes and corals in our systems. Here's a video of a sumpless, skimmerless, filterless system I maintain:

http://youtu.be/-eCQSVdqBQA