Having trouble keeping pH above 8.1

I need a little help figuring out a way to keep my pH above 8.1 in my 75 gal tank. I recently got a Pinpoint electronic pH meter and found out my pH tests weren't giving me an accurate measure of pH, since it was running around 7.9ish consistently with the Pinpoint. I used Seachem's Reef Buffer and successfully brought it up to 8.3 over a couple of days. The problem is that if I don't dose it a couple of times a day with Reef Buffer, it creeps back down to 7.9ish and I don't know how to keep the pH up consistently. I saw a big difference with my corals with the pH above 8.2, and I'd love to keep it there.

I'm considering getting a Kalk reactor with a pH monitor, but I wanted to ask the experts on this forum for feedback before I do. I also had considered a calcium reactor, but to my knowledge it doesn't help keep pH up, only Alk and Ca. And should my pH be dropping like it is?

Here's the info on my setup:

75 gal reef tank with 80lbs+ live rock
30 gal sump/refugium (cheato)
AquaC protein skimmer
Several LPS, Some SPS corals
10% water changes every 2 weeks
Phosban/Activated Carbon Media Reactor
Auto Top-off system with RO/DI

Water Params:
Salinity: 1.024
Temp: 79.5
Alk: 10.0
Ammonia: 0.0
Nitrite: 0.0
Nitrate: 0.0
pH: 7.9
Phosphate: 0.0
Calcium: 410

Thanks for any help you can provide.

Chad

 

Do you have a magnesium test kit? The parameters you listed look good but a low Mag reading can make it hard to stabilize your PH and Alk.

these are the commonly recognized levels you want, borrowed from Missionsix's sticky at the top of this forum

Magnesium/Mg-1400ppm This one affects the next 2 readings/levels.
Alk/dKH/KH-7-14. See chart above for conversions.
Calcium/Ca-380-500ppm

 

OK, PH like other parameter has “acceptable ranges” and you are at the lower end, yet its still ok. Since PH makes it easier for your corals to take in calcium carbonate I am not surprised that at 8.3 your corals appeared happier.

What is your PH at night vs. daytime ?

A calcium reactor is a decent way to go – [I have a PH probe, monitoring unit, and calcium reactor laying around….can PM me if interested] – the trouble here is that if you do not dial it in correctly you can end up with lower PH ! Reactors use carbon dioxide to dissolve the calcium media – generally if you aerate the effluent before it enters the tank your ok.

At first I was suspecting your Alkalinity, but at 10 DKH you should be good. Can you verify that this test kit is accurate?

PH is directly linked to oxygen and tank degas. I think it was Randy Holmes that suggested taking a cup of water, testing the PH and then aerating the water for an hour with an air stone – retest PH. This will rule out the a build up of Carbon Dioxide (or a lack of as well)

Here is a Link to Randy’s write-up on PH : Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com I hope this helps.

 

Crimson - Thanks for the reply, I actually found that post on Reefkeeping at around 2am before I went to sleep last night, and that was a great read. And no, I don't have a Mag test kit yet, but I'll sure have one before the end of the day. My pH drops about .1 overnight which I expected with the decrease in photosynthesis from my DT and I keep my refugium light on 24x7 so I'm not getting an offset from my marcroalgae.

I'll get an air stone today too and see if that doesn't affect my pH readings in a cup water. I have 2 fans blowing in my canopy and 2 blowing air out of my canopy, with another fan below on the sump/refugium to ensure I have good aeration, but I'd rather be sure that have to wonder.

I took organic chemistry 1 & 2 many years ago, and reading all these reactions (and trying to understand and apply them) is giving me nightmares thinking about those exams. Thanks for your replies.

Chad

 

Hello Chad, I use this product; Marine Reef Aquarium Additives: SEA-LAB #28 Automatic Replenisher it maintains Calc at 480-500 and buffers for PH. It is a good product. If you use it you eliminate "dosing" calc.

 

What brand of salt are you using? If you aren't already, I would suggest using a high quality salt for reef tanks with a high buffering capacity like Tropic Marin or another similar high grade salt. Using a salt mix with a naturally higher buffering capacity may help reduce the swings in pH you are seeing. I like to keep my pH at between 8.2-8.4 and I use Triple-Buffer to raise your pH and alkalinity occasionally when required.