Thanks for all the input. The whole acid thing sounds a little scary to me so I think that I will stick to water changes. This is the worst my tank has ever looked. The high alk is just the start of my issues as I had an automatic feeder and my parents opened the hole too much and there was too much food going in. I have algae every where and my tank smells horrible now. I'm trying not to freak out. Just water changes and cleaning everything and I am hoping that things will be all good in a few days.

How big is the tank? Can you do a 50 % change?

Johnny

IMO %50 water change is a bit too large for a system thats already stressed as there really is no need to drop your alk that fast lol.

i would do a smaller water change and let the alk fall normally , 12dkh or even 16dkh is high but its not crash a tank high , as long as your calcium is relatively in range and no precipitation then there is no need for acid or large water changes and other things that are just going to give you more instability.


if you never experienced any rtn then i would go about your normal water change amount to help flush the nutrients and allow the alk to drop over the next few days.

if you are previously dosing then obviously there was consumption to begin with.

Tank is 90 gallons. I am doing a 15 gallon change to begin with. I checked and the alk is 13.7 down from 14.4 so it is coming down. Ca is about 420. I just cleaned a power head that was really plugged up so things seem happier with more flow. It amazes me how fast algae can grow in 6 days. Hoping the sps will be happier after a water change and some more cleaning.

Continue on with your calcium dosing all will be well , that's a normal drop for alk so your going as expected.

IIf corals are growing they are consuming alkalinity , it has to be added so if you don't add anymore it will only drop from there . A fast drop is bad too but your levels are fine at that drop.