10 ppm no 3 and 5m of phosphate from tap. Considering ro

[twentyleagues]

Hi mate basically the KH in the tank was crashing down to about 2 when you add a large amount of water being 50% the water parameters would jump.

I think this was causing issues with some of the fry randomly dying when I done a water change in fact I lost a lot of Fry 2 or 3 would just die randomly after the water change.
I'm being advised to make sure my filters are pristin. And only changed the water as to the bioload. So I could definitely wrong about that I have I have ever heard from other people not to change so much water I'm definitely not an expert at this but personally from my experience large water changes didn't seem to work for me!

I'm not arguing the point, just trying to understand the circumstances. Did the fry die right after the waterchange? I get the point about the kh crashing but why? I have a large overstocked tank and usually do......lol and ive been trying to get to an anaerobic state in one of my filters to help control nitrates my kh stays at about 9. I do massive waterchanges weekly 75% or more. No issues. Try keeping the filters clean like said. I know there is alot of chemistry that goes into it that we dont all know about but its not that complicated or drastic in reality. Huge water changes happen in nature all the time. Also remember in nature only about 20% of fry actually make it to adults. I would continue doing waterchanges as needed or if you are worried about huge changes just do more smaller ones.