Reef Tank Calcium Test

high nitrates in Reef Tank?

i have always had high nitrates in my tank (20 ppm) but today i found my candy cane coral and my hammer coral not having its sweeper tentacles out which i found that weird because they always come out at night. i tested my water parameters and my nitrate are 40ppm, ph 8.0, nitrite and ammonia at 0. my calcium has been really high for the past month at 560 and my dkh has been really high too at 17. i use a di system for my water changes and top off. i have done so many water changes to lower my nitrate levels and nothing seems to bring it down. we have cut off the feeding because maybe we were over feeding and nothing. what can i do to lower my nitrate? i know my ph is low too. i put it some ph buffer to get my ph back up

For starters your problem right now is your alkalinity. That is most likely what is affecting your corals. Stop dosing the ph buffer. The PH buffer works by RAISING ALKALINITY!!! The DI cartridge you are using is most likely exhausted. You need to do some large water changes with real RODI water that you can get from walmart or your fish store. Test your tap water and post DI water parameters and you will find nitrate problem is most likely starting there. If you do not have a good protein skimmer than you should only be feeding the tank 2-3x a week.

How calcium and alkalinity function in the aquarium

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