You have a motoro in there. 15% a week isn't even close to what you need to do. I'd say 50% a week should be your minimum. Probably need to do more. Just let your water testing guide you.
i do 15 gallon every other day not every week
Sorry, man. I'm going to guess that it still isn't enough. It will only take you a few extra minutes to pull another 40 or 50 gallons out of there each time. That will probably get you closer to where you need to be.
it may only take a few minutes to take the water out but the hard part is putting new water in with only a 4 gallon bucket
I see. That would be a chore. I have a system with hoses for water out/in. I just let the science do the work.
what is your system to put the water back in?