This is how you should do water changes.
Since you have fish in the tank, it might not be in your best interest to take A LOT of water out all the time like you are doing.
Instead, take a smaller amount out when doing water changes.
Don't take out 70%, than add 20% wait 20 min and repeat that process, don't do that anymore. You are going to stress the fish out a lot.
You do not want to do this because Cichlids occupy the water space up to a foot above the substrate, but when you remove 70% of water at a time, you are reducing the height of avaliable water for the Cichlids to use, and by doing this, you are going to really stress the fish out.
yes did extreme ph and water change 2 days ago (dropped water level
down to 30% and added 20% waited 20 mins and dropped back down
to 30% and repeated cycle 4 times last cycle i added nutrelizer, ammolock
and plant food ph went to 7.6 and ammonia dopped down from 4 to .50
i am using an API freshwater master test kit
That is what you were doing, don't do this anymore.
Instead, when either your ammonia and/or nitrite is high, do a smaller water change, like 30%, and then immediately add back water that is around the same temp that has water conditioner in it, filling the tank back up to the top.
Wait like 30 min, and check the water parameters again, and based on your readings, if you need to do another water change, just take out a little water at a time, and then add back fresh, same temperature de-chlorinated tap water
Hope this will help with your water changing issues.
Let us know how it works out!
-FHM