pH reading of 7.7

[swishyfishies]

I just got my test kits (Salifert) yesterday & I decided to see what the pH currently is in my tank (new set up, only saltwater in it at the moment) Well, on the pH test kit the results I got was the 7.7 on the color chart. Now I have read that anything below 8.1 is a dangerously low level. Is a newly set up tank going to always register this low at the beginning? If it matters I use RO water in my tank & my metals are at 3 ppm.

Also I am having a hard time understanding Alk & it's relationship to pH. How should I use the pH & Alk test kits in relation to one another? (wow the Alk test kit looks a bit complicated)

There are many things that affect PH. Ambient CO2, acids, poor gas exchange, fish respiration and on and on really.

Alkalinity is just as important though. It is a measure of the tanks ability to absorb acids and resist changes in PH.

In a newly set up tank low PH is normal depending on how it is being cycled, excessive dieing matter will produce acids as well as carbon dioxide. These acids act against the PH and pull it down.

PH should not be used as a guage to represent alkalinity, but alkalinity can be used as a "loose" guage for PH. That greatly depends on what is being used to maintain the alklinity however. There are many additives in todays buffers and other alkaline products designed to maintain PH while raising the alkalinity. In most cases if alkalinity is maintained properly and the tank has sufficient water flow and ample "surface area" for gas exchange, PH will most often follow and be maintained along with it.

In the beginning it is something I would not worry about while the tank is cycling. You will find that once things settle down, the reduced acids will allow the PH to come back up or at the very least be easily corrected.

For the meantime >>here<< is a very good article that includes related link that should explain in great detail about the chem relationships.

Cheers
Steve

[swishyfishies]

Ok so I have to check the Alk 1st & then the pH. I'll check out the article but I have been referred to a few before & I can't ever understand them.

Originally Posted by swishyfishies

I'll check out the article but I have been referred to a few before & I can't ever understand them.

That's okay, I never did at first either. The understanding will come along as you grow into the hobby, no worries there.

What you have said though is a good guideline. Check the alk first. Adjust if necessary and then concern yourself with the PH. Just remember that you should not check immediately after any chem additions. The additions will temporarily spike the readings and skew the results. Wait a few hours after additions before testing again.

As a personal reference, I always check/adjust alk in the early AM. That will allow the PH to settle out by midday and is also the best time to test the PH as it will have been greatly affected by the CO2 that algeas put out during the dark hours of night. Throughout the daylight hours these same algaes will expell oxygen instead and counteract the reduction in PH.

But as I said, these are things you can be concerned about closer to the cycle's end.

Cheers
Steve