High Nitrate Levels

[jfenton954]

My 75g tank has had high nitrate levels for a while now..... . Some of my acans are slowly dying I think because of it. The levels are between 60-80 ppm. I did a 40% water change a couple of months ago but that didn't seem to work..I also cut back feeding to try to help. I have a 10x10 screen with 4x 23w cfls that I change every 3 months. The screen seems to be thriving the best I've ever seen it. My bio load is 90lbs of live sand, 175lbs of live rock, 20lbs of crushed coral in sump and 14 fish. I run the lights on the screen 18 straight hours now, would running the lights 24/7 help get rid if the nitrates faster? (I would have put pics up but can't log into site through tap talk.)

[Floyd R Turbo]

A thriving screen can be sort of relative. I picture will tell the story. Try to find a way to post a few.

A few questions.

10x10 screen is 100 sq in / 12 per cube = about 8 cube/day screen. Is that how much you are feeding? Is the screen sized per feeding, or per the old water volume based guideline?

What is your Phosphate at? What do you use to test that?

Have you ever tested potassium?

Are your other general parameters in line? Alkalinity, Calcium, Magnesium?

Lights at 18 hours are really your max for CFLs. 24/7 will not really help, but you might be able to push it to 20 hours/day. Algae needs a dark period.

The first thing I would try is increasing the flow to the screen and the intensity of the light. So this would mean a bigger pump and higher wattage CFLs.

Or, you could decrease the screen size, which would increase the flow per inch of screen width, and then switch lights to higher wattage but less of them. Increasing intensity and flow will get more green algae growing, which filters best.

But...pictures are really needed to make a good recommendation.

[jfenton954]

A thriving screen can be sort of relative. I picture will tell the story. Try to find a way to post a few.

A few questions.

10x10 screen is 100 sq in / 12 per cube = about 8 cube/day screen. Is that how much you are feeding? Is the screen sized per feeding, or per the old water volume based guideline? Was feeding 8cubes a day went to 4

What is your Phosphate at? What do you use to test that? Haven't tested that

Have you ever tested potassium? No

Are your other general parameters in line? Alkalinity, Calcium, Magnesium? Didn't think that would be the problem.

Lights at 18 hours are really your max for CFLs. 24/7 will not really help, but you might be able to push it to 20 hours/day. Algae needs a dark period.

The first thing I would try is increasing the flow to the screen and the intensity of the light. So this would mean a bigger pump and higher wattage CFLs.

Or, you could decrease the screen size, which would increase the flow per inch of screen width, and then switch lights to higher wattage but less of them. Increasing intensity and flow will get more green algae growing, which filters best.

But...pictures are really needed to make a good recommendation.

[SantaMonica]

Yes the growth is good for its size, so it just a matter of needing a stronger/larger scrubber, or waiting for P to come out of the rocks.

[Floyd R Turbo]

I always ask the question on general parameters, Alk/Cal/Mag because those are the basic ones that those need to be right, and if one of them is constantly fluctuating this can cause unhappiness.

If P is zero, and N is high, then you're limited. So it might help to know where P is at. very high P can also cause problems. If N and P are both there and other fixes don't help, then you might test for K and see if that is low.

So, now to your pics.

Your growth looks pretty good! Large chunks and thick growth. Flow looks good from what I can tell, but do you know what it is (GPH)? Overflow fed or pump fed?

your lights appear to be pointed at a downward angle. They should be pointed perpendicular to the screen (horizontal). This will inscrease intensity. Looks like a cramped area though. Also you can remove the dome/cone reflectors, the CFL floodlights have them built in.

How often do you clean the screen?

[jfenton954]

My tank has been established for about 4 years now.

[Floyd R Turbo]

My tank has been established for about 4 years now.

If you have been on a ramp-up of nutrients, evident by the high N, this might be driving phosphate into the rocks. That means once you fix the issue and lower P in the water column via scrubbing, you might start to leech them back out. This is what SM was getting at.

[Garf]

Looking at your previous posts from 3 years ago,you've always had certain concerns with the effectiveness of the scrubber (lighting, pH levels,flow etc). Did you ever get it to work properly in reducing nitrates ?

[jfenton954]

oh sorry.... I didn't know that, I wasn't trying to rude. So stronger lights will do the trick??

[jfenton954]

Yes I did I was running perfect at 0 ppm for a long time then I bought some led grow lights that screwed in like the cfls and work got busy so my girlfriend didn't realize that little to no growth was bad so I've been trying to get the nitrates to go down now for a while now . Which makes sense now that MS said about the P in the rocks