Ph help!

[Lucas2n]

Okay I really need to pick some brains here. Been struggling stabilizing ph. One of my tanks has been fluctuating between 6.9 and 6.0. When I test the water straight out of my tap I get a 8.2 reading. The tank is currently reading .25 ammo 0 nitrite 30 ppm nitrate. If I do a 50% WC my ph will raise to about 6.9 from 6.0, but then fall to 6.4 overnight, then back down to 6.0 after 24 hrs or so. I think my issue here is a lack of KH in my tap water. I tested it and got 0-17 ppm, or 1 drop on the kit. Pretty much near RO levels. The GH is at 4-8 drops so pretty much where I want it for my bass and rays.
I heard many people say that I should leave some tap out over night then test it a while later and see if the ph has dropped at all, so I will try that tonight. Does anyone here have KH issues and use some sort of buffer to increase KH? I saw someone say using crushed coral in your filter can be a good buffer. they had suggested 1 cup per 40 gallons in a media bag.
(FOOD FOR THOUGHT)
One theory is heavy bioload casuing too much organics in the water building up, combined with not enough WC on the tanks causing the crashes. 40g breeder holding tank for 1 5" male BD ray

 

[esoxlucius]

I had similar problems. 7.0 PH from the tap but would plummet quickly. I got a tester kit and my KH was the lowest reading. So, no buffering capacity at all. And yes, if you have tanks with a high bio load this exacerbates the problem.

Crushed coral is a good fix. It stabilised my PH nicely. A word of warning though. Crushed coral will 'dissolve' away over time. It was only very recently that my PH was dropping again so I checked my bag of crushed coral only to find there were only a few fragments left!!! I refilled my bag and the PH is stable again now.

I found that how much crushed coral you actually need is trial and error. The 'recommended' levels didn't do much for me so I just added more and tested. Repeat this until you reach a steady PH level which you are happy with.

Good luck.

 

[Rocksor]

Beneficial bacteria require a carbon source, so the process of consuming ammonia or nitrites reduces your buffering capacity as time goes by (KH).

 

[duanes]

I built a fluidized bed reactor to buffer pH and alkalinity by using aragonite sand as media a couple decades ago.
It used about 4 lbs of the aragonite, but I had to regularly add more (@ weekly) as the sand dissolved.


It was about 4 ft tall, with an 8" diameter, but I'm sure a smaller version would have been sufficient.
Finely crushed oyster shell would be a reasonable, and less expensive alternative to aragonite.
These days I use shells collected on the beach, and placed under the effluent flow to sumps.

Whole shells dissolved at a much slower rate, so would not be as useful or efficient as something finely crushed.

 

[Lucas2n]

I had similar problems. 7.0 PH from the tap but would plummet quickly. I got a tester kit and my KH was the lowest reading. So, no buffering capacity at all. And yes, if you have tanks with a high bio load this exacerbates the problem.

Crushed coral is a good fix. It stabilised my PH nicely. A word of warning though. Crushed coral will 'dissolve' away over time. It was only very recently that my PH was dropping again so I checked my bag of crushed coral only to find there were only a few fragments left!!! I refilled my bag and the PH is stable again now.

I found that how much crushed coral you actually need is trial and error. The 'recommended' levels didn't do much for me so I just added more and tested. Repeat this until you reach a steady PH level which you are happy with.

Good luck.

Thank you all for your advice, I think the route im going to go is putting some crushed coral in a media bag and sticking it in my filter, as you said its more of a trial and error and the more I read on it everyone seems to just start with an amount test, add or subtract, and keep doing so untill the desired level is achieved. Trial and error!

 

[Lucas2n]

quick update if anyones interested haha. I let tap water sit out for about 12 hrs. Ph went from 8.2 straight out of tap, down to 7.2 this morning. I ordered some crushed coral. Cant wait to get my 6x2 back up and running and im sure my ray will be much happier. I learned with this setup, it takes time, I used to want to rush everything, now ive learned slow and steady wins the race haha.