Can't get Nitrates below 40mg/l

[algy1943]

Guys, I really need some help my nitrates are at 40mg/l and no matter what I try they stay the same, my tank is 250L but with the 90kg of live rock there is probably only 160L of water, I do a 10% water change weekly, yesterday I changed 75L and still the water shows 40mg/l, in the sump I have in the refugium, live rock and lots of chaeto, the filter consists of carbon in a very fine sock in the bottom, 4" of foam, floss, a Seachems di-nitrate filter and more floss, attached is photo's of my sump and a sketch

 

[bjohanson1234]

How often do you change the filter floss/pads? I would bet that they are collecting detrius and keeping your nitrates high.

How often do you feed? It might be too much.

I am sure someone else here might be able to give their input.

 

[dcantucson]

BJ beat me to the post so I'll add +1 BJ


Allen, I would remove all that crap like the filter floss and foam. You can leave the carbon. That could be source or part of it. How often do you feed?

 

[Bifferwine]

Yeah, all the floss and foam does tend to create high nitrates. I'd remove it all.

 

[Wes888]

I have a filter sock but I clean them every week or two. Otherwise they would create nitrate from the trapped stuff.

 

[algy1943]

BJ beat me to the post so I'll add +1 BJ


Allen, I would remove all that crap like the filter floss and foam. You can leave the carbon. That could be source or part of it. How often do you feed?

when the lights come on at 11am and again at 6pm

 

[algy1943]

BJ beat me to the post so I'll add +1 BJ


Allen, I would remove all that crap like the filter floss and foam. You can leave the carbon. That could be source or part of it. How often do you feed?

Right David I have removed everything from the filter chamber except the carbon is all that is required to act as a filter?

 

[Bifferwine]

You don't even need the carbon. If you have a protein skimmer and live rock, you will be set. Carbon helps if you have a lot of soft corals in your tank, and it helps to clarify the water. But it doesn't actually 'filter'.

 

[bjohanson1234]

How much do you feed at once?
Does all the food get eaten?
I bet that you are overfeeding a bit.


I only feed my tank about a quarter of a cube twice a week. I have two clowns and a lawnmower blenny.

 

[algy1943]

Yeah, all the floss and foam does tend to create high nitrates. I'd remove it all.

what type of filter have you got in your 90g ?

 

[Bifferwine]

what type of filter have you got in your 90g ?

None. Just a protein skimmer, live rock, and a refugium.

 

[algy1943]

How much do you feed at once?
Does all the food get eaten?
I bet that you are overfeeding a bit.


I only feed my tank about a quarter of a cube twice a week. I have two clowns and a lawnmower blenny.

Do yo mean a quarter of one frozen cube?

 

[algy1943]

None. Just a protein skimmer, live rock, and a refugium.

So all the brown crap the floss captured, where will that go?

 

[Bifferwine]

So all the brown crap the floss captured, where will that go?

I don't know... I don't really think it's a problem, because I don't see it in my tank. That brown crap is sitting in your filter floss and rotting away, releasing nitrates. I get detritus on the bottom of my sump, but I suck it out during water changes. The water in my tank doesn't look like it has gunk in it.

 

[algy1943]

So all the brown crap the floss captured, where will that go?

The fish I have now is
2 clown fish
2 humbug damsels
1 yellow tang
1 royal tang
1 regal gramma
1 6 line wrasse
2 fire fish
1 coral beauty
1 blenny
how often would you feed them and how much?

 

[bjohanson1234]

Do yo mean a quarter of one frozen cube?

Yes, one quarter of a frozen cube. The fish constantly pick stuff off the rocks.

 

[algy1943]

I don't know... I don't really think it's a problem, because I don't see it in my tank. That brown crap is sitting in your filter floss and rotting away, releasing nitrates. I get detritus on the bottom of my sump, but I suck it out during water changes. The water in my tank doesn't look like it has gunk in it.

do you get much algae on your glass, I get brown fog on my glass every day

 

[Bifferwine]

Not every day. After I clean my glass, it will usually stay clean for several days before the algae starts growing back. The algae on the glass is probably a result of your high nitrates, too.

 

[algy1943]

Not every day. After I clean my glass, it will usually stay clean for several days before the algae starts growing back. The algae on the glass is probably a result of your high nitrates, too.

What temperature and what salinity would you suggest I keep my tank at? and how often would you feed the fish I have got?

 

[Bifferwine]

Temperature should be between 76 and 82 degrees F (you'll have to convert that for me!). Salinity should be between 1.022 and 1.026. Those won't have anything to do with your algae, though.

I would feed your fish once a day, or once every other day. My tank gets fed one time every two days.