Weird low pH / high dKh issue

Something that has plagued my tank for a year... and now I'm noticing it in my new tank as well, although not as much:

Old tank - currently still limping along with a big crack. Use RO/DI water, and brightwell salt at 1.025. pH is generally 7.8-8.0, even at 10 dKh in the evening.

I'll check tomorrow when the lights are on and see if it's any different, but it is just something I've noticed and wondering if I should be worried about it.

At the moment the new tank is 14 dKh because I just added a bunch of buffer etc. and even then its only 8.0 or maybe a bit better.

So anything to worry about or am I overanalyzing? PS - I have been using the API master test kit but I just ordered the Elos brand pH as that is the highest recommended one.

 

IMO you should pick the ALK value and maintain a target value around 9-10. Do not chase the pH value especially when your test is questionable.

Avoid Alk swings of 10-14, such swings can cause significant issues with stony corals.

If you are going to rely on the pH get a probe, measure the same time of day consistently.

You should also get values for Magnesium and Ca to help you adjust the Alk accordingly.

 

A Ph of 8 is nothing much to worry about
although growth may be better in hard corals, with a slightly higher Ph

it has been shown by a few studies that carbonate uptake by stony corals has been improved in Ph over 8.2

Dkh of 14 is more of a concern so using a Ph buffer that increases Alkalinity is not always the answer to the problem of low PH
I would allow that to fall and then maintain it somewhere between 7 and 11

it is often the case that low Ph is as a result of carbon dioxide levels within the aquarium and within the room that the aquarium is located

you can prove if this is the case, by taking a sample of the water
and using an air pump, air stone combination, outside if possible or near an open window
leave the water bubbling away for an hour and then re test Ph, if it reads higher, that does indicate Co2 was the issue

to solve the problem in the aquarium
increase surface agitation
open windows in the home as often as possible
consider running air from outside into your skimmer

Steve

 

Thanks guys, appreciate the tips. New tank is down to 12 dKh this morning. I will try the air suggestion and see if its a CO2 issue.

 

I am sorry, but I am not really understanding your problem here.. If I missed something please let me know..

A pH of 8 is fine. You want to keep it between 7.8 and 8.3. The key here is that you are using a buffer. The carbonate buffer system is one of the most vital buffering systems for all living organisms. The major idea here is that the buffer solution allows your aquarium water to RESIST changes in pH. By adding more buffer, you are likely increasing your tanks ability to resist large pH changes. If there was no buffer, your tanks pH would be swinging all over the place. One key purpose here is to resist pH changes from varying CO2 content (due to varying production from respiration, and consumption from photosynthetic organisms at different times of the day). This is just like the carbonate buffering system in your bloodstream when you are breathing. Sometimes you breath slowly, sometimes rapidly. The system is just constantly shifting towards equilibrium (bicarbonate<->carbonate<->carbonic acid) and the buffer is just donating and accepting those hydrogen ions to basically eliminate the pH changes. In other words, don't think too much into it. I just did it for you.