Low posphate high nitrate

[Reesj]

Hi,
I have my tank running for about 10 months now. 50 gallon reef tank with about 10 gallon sump. Got mostly LPS, zoas and a sun coral colony. Tank is a bit under PAR for light and hoping to increase in fw weeks when I get some equipments. I feed reef roid almost every other day for my sun corals at evening with return turned off for 2-3 hoours. Got a skimmer and almost non fuctional algae scrubber running. Also got mechanical filteration in sump.

Anyway, I had been testing so far with salifert Phospate and the reading currently seems <0.1. But recently my GSP seemed to have slowed the growth and not coming out completely. So I bought a Nitrate test kit (Not salifert)tested. The reading was around 20-40ppm. Seems quite high for having PO4 0.03-0.1.
Alk= 6.5-8
Cal= 440-450

Any ideas how to reduce the nitrates when the posphates already seemed to be bottomed out ?
Should I reduce my reef roid feedings?

 

[Lasse]

Reef roid is high in PO4 - in my experience - your problem is probably not caused by high NO3 levels. If you can validate your PO4 levels would help. There is a risk that your test not show the right value. Some of your observations -

GSP seemed to have slowed the growth and not coming out completely

- can indicate a low PO4 level (below 0.03) If you think this is the problem - you can test with feeding reef roid every day.

Sincerely Lasse

 

[naterealbig]

Three ratio (and level) of phosphate to nitrate looks great to me. The assumption, of course, is that your phosphate is not zero. Like @Lasse said - it likely is not zero if using Reef Roids at the frequency you are using. The ULR Hanna Phosphate Checker could help you confirm the level.

 

[Reesj]

Thanks for the reply. I guess I had been running skimmer about 80% of time now than previous 50%.
Problem with Salifert PO4 test kit is the small numbers. The test is not completely white and I can see a hint of blue in it. But Hard to say how high it is from 0. Clearly it is not above 0.1. But no idea where from 0 to 0.1 range. We also don't have any fancy test kits here yet.
So do you guys think, that 30-40 nitrate level, (if reading is correct) is alright for a very low phospate value ?

 

[naterealbig]

If I had my way, I'd keep nitrates around 20-30. 30-40 seems a little on the high end, but different systems are different. If your corals are happy I would leave it there.

 

[blasterman]

30-40 is a bomb waiting to go off in my opinion. My next opinion is ReefRoids are worthless. The only benefit of these products is they keep P04 and nitrate elevated, and that keeps lps and softies happy.

 

[Uncle99]

I would have expected more like 2-10ppm with a phosphate of less than .1
You could carbon dose that nitrate down a bit, carbon dose has little effect on phosphate.
You also mentioned AlK 6.5-8.
6.5 is low, 8.5 is fine, but the variance should stay within .5 dkh.

I might agree with nitrate in the 30-40 range in a real mature tank, but not in one that’s 10 months old.

 

[Cwentz758]

I think he meant 6.5 - 6.8. If that’s the case you’re still on the low side.

 

[Reesj]

I would have expected more like 2-10ppm with a phosphate of less than .1
You could carbon dose that nitrate down a bit, carbon dose has little effect on phosphate.
You also mentioned AlK 6.5-8.
6.5 is low, 8.5 is fine, but the variance should stay within .5 dkh.

I might agree with nitrate in the 30-40 range in a real mature tank, but not in one that’s 10 months old.

I used to dose vinigar small amount (3-4 ml every other day) for about 2-3 months. But with that, quite a thick film coating tend to get on the front glass That is in top of a exploding Trochus snail population i have to throw back to the ocean to keep in control. So i stoped carbon dosing about 3 months back.

Nitrate might be closer to 30 in reality than 40. Test kit colour is brighter than 20 , but a lot less than the colour at 50.

My tank Alk had fallen last time i checked unfortunetly to about 6.5.(haven't test in twow weeks) I try to keep it at around 8 and make my water change salt at 8 dkh. So thats why I said it is 6.5 to 8 range. Tank currently might be around 7 and i'm slowing dosing baking soda to get it up.