I constantly get a high nitrate reading. In the last 4 weeks we have taken the following actions:

Increased the water movement by adding an additional pump
Changed the sand in the sump tank
Increased the water changes
changed the filtration floss to another type
Tested the RO water that we use and it is reading fine
Reduced fish feed

Over the past few months we have lost corals and have a dark red algae that needs to be cleaned out of the tank almost daily. In the past 4 weeks we have not lost any more corals however the algae problem is still there.

Does anyone have any suggestions as to what else we can do to get rid of this problem please ?

Hi Grace,

You could also check for phosphate too. Additionally to checking the RO water also check it once the salt is mixed too and ensure that the salt doesn't contain phosphates or nitrates.

Basically you're doing the right thing, the quickest way of lowering undesirable levels is through water changes - so keep on with that.

The other thing is that rocks and coral sand can absorb phosphates and nitrates over time and then release them again. You may want to ask what phosphate and nitrate removing products they have at your LFS - and do they work. Many products say they remove these - but most don't work or don't work as effectively as we would like.

Not all activated carbon products were created equal, if you use activated carbon try and verify with a quality LFS that these are phosphate and nitrate free.

If you have a lot of fish in your system the best way to controlling levels is through water changes.

You could also add turbo snails (the cone shaped ones) and red leg hermit crabs - these are pretty effective in helping algae control - not sure they'll eat red algae though.

Because biological filtration is so efficient at converting nitrite to ammonia to nitrate you could always rinse out your filter floss at least weekly in water from the aquarium to clean it and at the same time not kill any beneficial bacteria.

Another thing to note when you water change is to mix the water and leave it to aerate for at least eight hours preferably up to 24 hours as there are a great deal of chemical reactions going on when salt is mixed. Your corals will thank you for it.

Mark
ATF

Hi, thanks for your suggestions on how to resolve our problem. I am working through them!. I have tested my RO water after the salt is added and Nitrate and Phosphate levels are fine. I have now upped my water changes and doing large changes daily to see if the levels improve. Thanks again

Grace

You're welcome Grace, please pop back and let me know how things are going in a couple of weeks or so. Best of luck - keep up the good work!

Mark
ATF