Driftwood Keeping Kh Down? Help Please.

[Gage Zamrzla]

I'm having some issues with my 75g tank. It is overstocked at the moment with 1 10" IT, 13 2"-5" CL and 3 3"-4" Dats. I run a Fluval 305 and Fx5 with sponges on the intakes and I have Koralia powerheads (750gph and 1400 gph) to disturb the surface from side to side of my tank.I had an Imodium(spelling?) issue but have since altered the stock and added an Fx5 to provide more media/bacteria. During the imodium issue my Kh dropped considerably low and my Ph did the same as a result. I don't remember the Kh levels but I'd say it was lower then 17.9 and my Ph was bottoming out at 6.0 on my test kit so I'm assuming it went lower. The tank was back to normal for a few weeks or so I thought. I have no signs of ammonia or nitrite, and nitrates are usually between 10-40ppm. My Ph and Kh however are still majorly low, right back down to 17.9 and below 6.0ppm. I have black Tahitian sand and some river stones in the tank and I know neither of those lower the Kh. I also have 3 medium/large pieces of driftwood (depending on what you'd call big. They fill a little less than 1/6 of the tank. I do 50% W/C to keep the Kh and PH as neutral as I can but within 3-4 days it always drops back down. I'm wondering if the wood is keeping the Kh from stabilizing? I just want my tank to be at least neutral and not super soft. I somewhat understand the working of softness and alkalinity but I'm sure I'm far off point on more than a few things.

So, might the driftwood be keeping the Kh from stabilizing when I add new water into the tank?

What can cause Kh to continually drop?

What can I do to solve the cause of the Kh drop?

Will alkaline buffer or regulator
or neutral regulator solve this problem (not band-aid it, solve it by stabilizing my kh for the long term)?

If you have any other suggestions or there's something I missed please bring it up. And sorry if some of this is rookie stuff I'm spacing or forgetting, working with over 100 tanks during the day and then when the time comes for my tanks at night I'm crashed out and can't think straight.

 

[Gage Zamrzla]

BTW most of these fish will be upgraded soon and this tank will end up being a community tank. I really just want to fix this for the experience and to have less stuff to stress about.

 

[Gage Zamrzla]

Also all the fish seem happy enough but I'm concerned because I'd read that if Ph is lower than 5.5 nitrates start to dissolve or something like that and that would obviously not be good.

 

[deeda]

What is the pH and kH of your tap water after it's been sitting out for 24 hours?

I have driftwood in my tanks and have not noticed any drop in kH at all.

 

[Gage Zamrzla]

I don't know, I'll fill a 5g bucket and see. It shouldn't be as low as it is in my tank. Unless the water system my city used made some major change overnight, and if it is my tap water then all of my tanks should have the same results which they don't. Like I said I'll give it a shot and see what happens to it.