Truth and understanding of nitrates in a fowlr

[lion king]

I don't get it, why am I so concerned; so obsessed with nitrates in my fowlr. If your tank looks good(manageable algae) and your fish are thriving, should we be so concerned about nitrate levels. 20 years of marine fish keeping of large aggressive fish and I never even tested for nitrates pass the initial cycling of a tank. Many tanks, many fish; fish I kept for decades. Rarely lost a fish except an occasional new arrival that would just drop dead explainable. Fish that went on to very large professionally maintained aquariums, good looking tanks, healthy vibrant fish.

After about a 5 years hiatus I returned with an interest in reefing, so now all the testing. 5 more years my reefing interest has waned; I still keep 1 reef, but have 3 fowlrs and a macro tank. I have a 125g fowlr that no matter what I do I can not bring the nitrates down, off the charts. Don't suggest anything I know about most and am or have tried everything.

The point is; the tank looks great, the fish are thriving and beautiful. Should I even have a concern.

 

[andrewkw]

IMO no. Nitrate is toxic to fish at what 500ppm? Maybe more. Now if you have some sensitive / expensive fish maybe it's more of a concern or inverts like starfish ect but for predator fish or really any non sensitive fish I personally don't see it to be a concern. That being said the nitrate in my fowlr is quite low which somewhat surprised me when I tested. You mention off the charts. How high off the charts? Maybe consider a 100% water change? You could carbon dose as a less labor intensive solution. One of these solutions could get you back on the chart at which time I wouldn't worry.

 

[lion king]

Off the charts of a red sea test kit, so just over 50ppm as it looks. I've done 100% water changes over a couple of days or so. I have a refugium of about 23g volume, I dose nopox, and just added a brightwell no3 xport brick, I also run chemipure elite. The main culprit is a jeweled moray eel, so don't take lightly what an eel can do to the nutrient level; they are messy.

***Darn it, I just figured out why the nopox wasn't working; I was still running purigen in that tank. Seachem reports that purigen will remove some of the elements from the nopox and make it ineffective.

 

[Waters]

Also, have you tested your replacement water for nitrates? After doing 100% water changes, your nitrate levels should be much lower than it appears they are.

 

[mcarroll]

Check your PO4 levels. Maybe zero. Nothing will grow and eat the nitrates without some PO4 available....not even the denitrifiers that you want to populate the bio-brick you got.

Also...

Nitrates aren't directly toxic per se, but if I recall correctly they can still have an effect on metabolism. I wouldn't act hastily in any way – you're right on presuming to do nothing – but I'd probably also try to figure something out to alleviate the situation.

Growing a nice crop of corals is the best way to use up dissolved nutrients IMO, but macroalgae or an ATS should take care of it too – if there are available phosphates and other nutrients in the water.

Another alternative is to hook up a deep sand bed to the system.....bigger is better. (Nutrients still have to be in order. Zero PO4 is a general deal-breaker.)

 

[lion king]

Phosphate at ~ .36, probably low in relationship to the nitrates; but not zero. The main observation is that "do not underestimate the messiness of an eel". I have other tanks with big eaters, and I have the tendency to over feed. But nothing like this, I see the eel grab food take it back in his cave, shake it around; bet there's just rotten food in there.

 

[mcarroll]

Gonna have to experiment and see if there's any CUC he'll allow to live in there.....try smaller snails....cleaner shrimps....etc. If nothing works, and you're right about the rotting food, then that's worth taking action on. Have you tested for ammonia and nitrite by any chance?

 

[mcarroll]

Maybe consider an alternate diet too...

 

[lion king]

Ammonia and nitrite zip, it;s otherwise a healthy tank. Had it not been for the obsession of testing, I'd never have known or even concerned myself. It's my juvi trigger tank so cuc is out of the question, if I even dangle a finger the blueline bites me: I've tried. I have some algae but nothing a monthly scrubbing doesn't take care of, it's still a nice looking tank. Like I stated above I kept predator tanks before and never even tested for nitrates. I kept a 180 for over 10 years with 3 triggers, a puffer, and lion; running just a wet/dry with no skimmer or refugium. I was just curious if all this testing and obsessing might be a little overblown.

 

[mcarroll]

Sounds like no worries then. I just don't like the idea of rotting food in the tank....can't tell from here whether that's a true worry tho...I just know you mentioned it.