Chronic Low PH

[ImagineAquatics]

I have a very stubborn mini invert only aquarium (<10 gal), and its PH hovers around 7.5. I can't seem to get it to come up.

I am trying to move away from frequent water changes (10-15% per week) and adopt a dosing regimen that has been suggested to me by GARF.ORG. I'm sure the water changes have been contributing to the low PH (DI water, Kent marine salt). I have tested the change water at a Ph of 7.6 after mixing.

I have a 3" argonite bed with about 10-15lbs of argonite concrete pseudo live rock (aquicultured). Ammonia levels well below the line. There is no skimmer on this unit.

I have been trying to use SeaChem Reef advantage calcium (once per month, one Tbsp per gallon of makeup water), which is the only ph affecting supplement on the list. However, I don't really have too much water to makeup in this small tank, though (1 cup or so per month), so not much of this is getting added (unlike larger aquariums). I do have overflows, which probably adds to the CO2 levels..

I'd prefer to get the levels under control without buying more supplements. I'm reasonably sure that it's just a matter of having enough buffering agent in the water, but I'm not exactly sure how to do this with what I have.

Any ideas?

BTW, the dosing regimen that I'm going to try is:

(All Seachem)

1/2 Teaspoon - Reef Plus twice a week
1/2 Teaspoon - Reef Complete twice a week
1/2 Teaspoon - Reef Calcium twice a week
1 Tablespoon - Reef Advantage Calcium added to each gallon of makeup water during the 2nd and 4th weeks.
1 Tablespoon - Reef Builder added to each gallon of makeup water during the 3rd week of each month.

[ImagineAquatics]

Hmmm... I may have answered my own question. Seems I should be using reef buffer, according to the seachem website. According to an article there, it could be my argonite concrete and substrate that are bringing my ph down --- http://www.seachem.com/support/Articles/MarinepH.html

How important is pH relative to alkalinity? I've heard so much conflicting info that I can't really sort it out. Most of my inverts are being fruitful and multiplying, though a few are growing much more slowly, or not at all. I have a fox coral that has even receded a bit.

[Fishfirst]

I'd try natural methods first such as some crushed coral or some liverock. Try slowly switching to instant ocean sea salt, I believe it has higher alk and pH. Also what is your sg/salinity? This has an important affect on pH.

[TheOldSalt]

Definately lose the Kent salt & replace with Instant Ocean. There's just no excuse for newly mixed synthetic seawater to have a pH of 7.6. With I.O. it'll be 8.3 or so, and it'll stay there awhile.

The web article you linked to is a bit suspect, to put it mildly. Atoms exchange electrons all the time, but PROtons? Maybe in an antimatter universe. I have to go to work now.

[ImagineAquatics]

You know what, I thought that part was a bit odd. I figured they were talking about the H+ ions. They wouldn't have electrons in this ionic form, I don't believe.

And about the kent marine salt, I only picked it up because my supplier was out of the instant ocean. I thought it was odd that the pH was so low, but I JUST got a new RO+DI unit when I got this new salt and I thought maybe that had something to do with it. I was using just RO before, with instant ocean.

Also, I just started a few new tanks with this new salt, and those ALL have a low pH. I suspected the water, I guess, and not the salt. I'll toss it out. Thanks!

[ImagineAquatics]

Oh, and about the crushed coral, the argonite concrete I made is 1/5 argonite sand, 3/5 crushed argonite and oyster shell mix (oyster shells are cheap ), and 1/5 portland #2 cement, so there's plenty of pH affecting substrate. The specific gravity is about 1.024.

It'll take a few days to get the Instant Ocean in, but I may have an idea. I'm a bit unsure if it is good for the tank, but maybe someone here has the answer:

I have about 100lbs of semi-cured concrete rocks (as explained above) sitting in a bed of freshwater. I changed the curing water today. Before the 100% change the pH of the freshwater was about 10.5. 12hrs later the pH is at 10. The change was rapid, but there is a LOT of rocks in a small amount of water. I'm wondering if I can add a small piece of this rock to my aquarium and monitor the pH until it comes up to around 8.3 (hopefully in a week or so). I have a continious pH monitor, so I could check on it frequently. I could also replace it with a smaller piece if the pH comes up too rapidly. Would this work, or is it dangerous? Does anyone know what effect this would have on alk?

[Fishfirst]

if your inverts are doing alright right now I wouldn't change anything except start slowly doing water changes with IO

[TheOldSalt]

That just might work. It'll raise the alkalinity, even if only temporarily, and a small enough pice won't bring up the pH fast enough to cause problems. I would suggest putting the rock in the filter or sump, not directly in the tank. That will get it's effects evenly distributed throughout the system, instead of having a hot zone near the rock which could be harmful. ( in a tank with insufficient circulation )
A rise in pH is a risk, so be careful. at 7.6, a lot of the ammonia in your tank will be in the form of ammonium, which is relatively harmless and not as easily digested by the bacteria. When the pH shoots back up, the NH4 will become NH3 ammonia again, and this can cause a whole new mini-cycle. It's usually not a problem at all unless the tank is overcrowded or has been running at 7.6 for too long. Just be sure to watch it.

By the way, are you mixing the Kent salt with the RO water as soon as the water is made? You might get better results if you aerate the new water for a day before mixing. It's worth a shot.

[ImagineAquatics]

I have been just mixing it straight away. I have about 25 gal of the salt left, and I was planning on adding the curing rocks to my mixed water until the pH comes up where it needs to be.

I added some of those rocks (about 1.5 lbs, 3 weeks curing, to what you could call a sump) to one of the tanks (very lightly populated) and the pH has been coming up at a rate of about 1/10 point per 6 hrs. I haven't seen any negative results yet. BTW, I don't have a good alk test, so I have no idea what the levels in the tank are. That's the next item on my equipment list.

I'll watch the ammonia levels in the tank closely, thanks for the tip. I had not thought of this.

Regards,

Brad