PH 7.4 to 8.8 in one hour, now what

[lecroj]

I hadn't tested PH in a week and it was 7.4 (tested twice). Last week it was 8.3. I added 2 cap fulls of carbonate and the PH shot up to 8.8. Mushroom and anemone now are sagging and a bit floppy. I did just add RowaPhos to the system yesterday so I don't know if that could drop the PH. It isn't CO2 because I have a pump and two powerheads running and a skimmer that makes tons of bubbles. I don't want to shock the tank again. Is there anything I should do or just wait it out?

 

Salt 1.024

temp 78.3

Ca 460

Mg, didn't test but last week it was 1300

KH 9 before I added two caps of carbonate

PO4 0.5

Ammonia, trite and trate all 0

Last water change 3 days ago, 25%

22 gal tank

[lakshwadeep]

2 capfuls???

What product are you using?

What test kit brand(s) are you using?

 

It sounds like your carbonate addition caused a pH spike, which is kind of normal. Note that you should only be adding carbonate if your alkalinity, not pH, is a problem because that's what the alkalinity test measures (carbonate/bicarbonate). A "capful" is a fairly imprecise way to dose a tank. Read this article on supplementation:

http://reefkeeping.com/issues/2007-04/rhf/index.php

[lecroj]

I used seachem carbonate. It says one cap full per 20 gal to raise KH .25.

From my chem classes 20 years ago, I thought alkalinity is base and acidity is acid, both ends of the Ph spectrum. From the results of this unplanned experiment that still seems to be true since Ph shot up by 1.4 when I added alkalinity.

My main question is, should I let the tank ride this out or add something like vinegar to drop the PH back to 8.2 or 8.4?

[lecroj]

Sorry, i had it wrong. Alkalinity is a buffer, but i would guess that carbonate must have a naturally high Ph even though it is a buffer.

[lakshwadeep]

What test kit brand(s) are you using?

 

Don't add anything; the pH will be fine. Whenever you add a high pH additive like this, you have to add it slowly so there isn't a sharp spike. It's also best to add it when the pH is lowest (usually in the morning before the lights turn on). The excess carbonate will probably lead to abiotic precipitation of solid calcium carbonate, so your calcium levels may be depleted. This also highlights the need to monitor calcium as well as alkalinity whenever you try to dose either one of them. This is where the section in my previous article titled "Calcium and Alkalinity: Fixing an Imbalance" is important.

 

KH stands for karbonate harte (carbonate hardness), referring to carbonate and bicarbonate ions, the major ions in saltwater. This is a good article explaining alkalinity.

http://www.advancedaquarist.com/issues/feb2002/chemistry.htm

[lecroj]

I use API for everything except Mag. Mag was 1375 today, Ca 460, KH 10 (was 9 before I added all the carbonate) Ph 8.2, Phos 0 after adding the rowaphos a few days ago. Things look fine except the Ph which seems like it is slowly falling again. I still think the rowaphos has something to do with the Ph falling.

 

I freaked yesterday because I had fish and corals coming today. All the zoa, ricordea and frogs spawn are open and look happy. Fish all seem happy so I won't worry about it unless Ph falls again and I may point a powerhead at the surface to take CO2 down more.

 

What would you do if the Ph was 7.4 and other parameters were fine?

 

What about adding baking soda if the Ph drops again? Also, do people bake the baking soda first and if so why?

[lakshwadeep]

Read this article on pH for ideas on dealing with low pH, and get your water tested with a different test kit to be safe.

http://reefkeeping.com/issues/2007-05/rhf/index.php