Coral and High Nitrates

[bearcatbomber]

I have 2 tanks, a 14g biocube thats been running for almost a year (one more month!) and a tank thats about 5 months old, 20g tall with some nice lighting. Until now, the 20g has been FOWLR, and the biocube has coral in it. I got some nice new ones, and they look pretty good in the cube.

I upgrades my lighting in my 20, and want to switch coral over to it. I tested the water 2 weeks ago, and the nitrates were almost 25ppm, simply from neglect I did a series of water changes, and its down to below 5ppm to get it ready for the transfer.

I was going to be switching the coral over today, and randomly I tested my biocubes water, and its at 15ppm.

Now, how exactly have star polyps, button polyps, hairy mushroom, a duncan, and a flowerpot coral been doing well in a tank with nitrates that high? Theyve been in there for 2 months. Not only do they stay open, but they've also been growing, especially in the past month. I'm not understanding it.

[Squiers007]

Nitrates typically do not effect those types of corals much until they reach much higher levels say around 70-80ppm. 15ppm is not considered to be very "high" while it would be beneficial for the tank to remain below 10ppm, having it at 15 for a short amount of time should not have much of a negative impact on your corals.

[bearcatbomber]

I just find that weird because everything I've ever read says that your tank should be <1ppm if you have coral.

[Squiers007]

You ultimately want to strive for an ultra-low nutrient tank, but since many people keep lots of fish maintaining nitrates below 1ppm can be difficult. In my experience if you can keep your nitrates below 5-10, there should be no negative impact on any of your corals.