um... pH 8.8?

[Taqpol]

So according to my API test kit my pH of my newly established (three week old) tank has skyrocketed to 8.8. I did the test twice, both to the 5mL line, and used 5 drops of the chemical. On Thursday my pH was at 8.2-8.4...

All my other readings are perfect:
Ammonia: 0 ppm
Nitirite: 0 ppm
Nitrate: 0 ppm
Salinity: 1.024

There is a massive bloom of brown algae covering everything. I hope this can help you guys, whats wrong with my tank?

[kau_cinta_ku]

High pH: Causes and Cures
http://www.reefkeeping.com/issues/2005-03/rhf/index.php

[Taqpol]

Well, I've now thoroughly read both the articles on high and low pH. Thank you for that link, I wasn't even thinking. I am still a little confused though.

I haven't been dosing anything at all, much less something prone to cause pH problems. I did do my measurements at the very end of my DT's main light cycle, when the author states that pH should be the highest because alot of the CO2 has been used up by photosynthesis. I do however have a HOB refugium with chaeto on the opposite photoperiod that should be combating this problem. Is the problem potentially due to my excessive amount of algae going through photosynthesis and using up CO2. If so, should i turn off my lights for awhile?

Also, I have currently decided to try pumping air into the tank short term via an air pump w/ stone. Is this a good idea?

[kau_cinta_ku]

what are you using to check the pH? have you tried a diff. test kit to confirm that it really is that high?

right now I wouldn't do anything but try to have someone else test it with a diff. test kit. as stated in the article anything over 8.5 is usually a error in the test kit.

[Taqpol]

I'm using an API test kit. I'm probably going to be running to my LFS tomorrow, but i think they use API for there tests as well...

Do you think it would be safe to add a snail or two under these conditions?

[kau_cinta_ku]

yeah they will be fine.

even if they use the same brand test kit, it would still be good to get a second opinion.

[Randy Holmes-Farley]

Unless you were using limewater, and a ton of it, the pH 8.8 is almost certainly measurement error. That is the case for 99+% of such "occurrences". :)

[Taqpol]

Thanks for your help!

[Randy Holmes-Farley]

:thumbsup:

Good luck. :)

[Taqpol]

Yeah, tested it this morning (after running an airstone all night) and it looked like the pH was down to 8.0-8.2. I always forget, does CO2 increase or decrease pH?

[IslandCrow]

CO2 decreases your PH. Your current readings sound much more likely. I don't know how much the airstone helped, but I'm with Randy in thinking those first readings were somehow in error. Hopefully, that airstone isn't your primary method of water circulation. If it is, you'll really want to go with a powerhead instead. About the only time people use airstones in saltwater tanks is as an energy efficient backup when the power goes out.

[Taqpol]

No, I have a Koralia 1 blowing behind my rock work, a MJ900 aimed at the surface for agitation (oxygenation), and a 100gph pump working my hang on back fuge. All of this in my little 20 gallon high.

Thats why I was so confused. The article says this normally happens when your water has poor oxygenation, but with my MJ900 and a fall in the fuge I've been thinking my oxygenation should be really good.

[Randy Holmes-Farley]

Well, strictly speaking it is not oxygenation but aeration to drive in or out CO2. Your "problem" is likely measurement, not the aeration. :)

[Taqpol]

Ok, thank you for all your help!

[otrlynn]

To RHF, just because I'm curious, does using an airstone "inject" 02 into the water, or allow C02 to escape? What about the air mixed into the water via the skimmer?

[Randy Holmes-Farley]

Any form of aeration can drive any gas into the water or out of it, depending on whether the water has a deficiency of that gas or an excess, relative to the air.

So, for example, if you have normal seawater at pH 8.5, which has a deficiency of CO2, aeration with normal air will drive CO2 into the water and lower the pH. If normal seawater is at pH 7.8, where it has an excess of CO2, and you aerate it with normal air, CO2 will be driven out, and the pH will rise.

Same with O2. If the dissolved O2 is above saturation, aeration will drive some out. If it is below saturation, it will drive O2 into the water. If it is exactly saturated with O2, there will be no net change. :)

The excess or deficiency of O2 has little bearing on the excess or deficiency of CO2, and vice versa.