Phosphate testing

[bureau13]

So I've been battling this SUPER high nitrate problem, and it just never goes down. At this point I'm thinking it has to be the deep sand bed so I've started cleaning that, which is terrifying, but no ill effects so far. Also no measurable reduction in nitrates, but a lot more to do.

One of the weird things about my situation is that, using the Salifert kit, phosphates are usually showing as 0, or at the worst, 0.03 or whatever the next one from 0 is. So I thought I'd get the Hanna ULR tester to be more accurate. It just measured 0.14. what the heck. Very big difference. One (at least) of these kits would seem to be completely worthless.

 

[KrisReef]

That is a big enough difference to make a person doubt both test kits, for sure. It it one of the frustrations of our hobby test kits, we have to presume that they are giving us reasonably accurate results but verification by using another hobby kit is not going to be comforting when the results are this far off.

Can you post a picture of your tank? Have you noticed any issues with your fish or coral, or are the numbers the soruce of concerns?

 

[Reef.]

Salifert is terrible for testing below 0.1, chances are the hanna is correct, especially if high nitrates, as it’s unlikely for nitrates to be so high but po4 zero.

Water changes are the best way to lower nitrates, you will lower nitrates directly related to the percentage water change, 20% water change will lower nitrates by 20%, a couple of those and you should be where you need to be.

How deep is your sand bed and why do you want a deep sand bed, if for no good reason, removing some sand would probably be a good idea, as keep doing big water changes is not ideal, getting to the root of the problem of why your po4 and nitrates are high is better than just trying to keep reducing your nutrients.

 

[gbroadbridge]

One of the weird things about my situation is that, using the Salifert kit, phosphates are usually showing as 0, or at the worst, 0.03 or whatever the next one from 0 is. So I thought I'd get the Hanna ULR tester to be more accurate. It just measured 0.14. what the heck. Very big difference. One (at least) of these kits would seem to be completely worthless.

Salifert is only useful above 0.1ppm Phosphate

Below that you use the Hanna.

 

[bureau13]

Some other info: The ICP test I did a couple months ago showed phosphates at 0.05. I just tested again and got 0.03 Salifert (maybe.... Looks a lot like 0 as well) and Hanna 0.07. Quite a bit better than before I guess.

Other info: This tank has been up and running for at least 15 years, but the last several were highly neglected due to a crash and no livestock remaining. About a year ago I did a bunch of water changes and added some fish and a few corals. Other than a couple fish that didn't survive the transition to the tank, the fish seem very active and healthy. Stony corals have not done well at all, but some zoas and other softies have done fairly well.

Sand bed is 5-6". I've been dosing carbon but it's not really helping, and I've also done a lot of large water changes. However, the Nitrates according to the ICP were 199

Lousy pic below: