i need input please

[Joker]

I think I may have found my problem but I'm not 100%. When I do water changes I have been using a pump that water gets inside the top of it. I have just srugged it off and never thought it was hurting my tank. Now thinking about it for a while I remember after each water change the corals would close right up but a few hours later they would open back up. I never ran carbon so this toxin that the pump could be pumping into the tank has been building up for months now. I started to use carbon and it seems like the corals are starting to perk right up still not 100% yet but slowly showing signs. I just seen this stuff called cuprisorb and was thinking of giving it a try, what do you guys think?

 

[BiGGiePauls33]

I think I may have found my problem but I'm not 100%. When I do water changes I have been using a pump that water gets inside the top of it. I have just srugged it off and never thought it was hurting my tank. Now thinking about it for a while I remember after each water change the corals would close right up but a few hours later they would open back up. I never ran carbon so this toxin that the pump could be pumping into the tank has been building up for months now. I started to use carbon and it seems like the corals are starting to perk right up still not 100% yet but slowly showing signs. I just seen this stuff called cuprisorb and was thinking of giving it a try, what do you guys think?

What pump are you using?

 

[Joker]

What pump are you using?

This is the pump

This is where the water enters