Battling against a low ph

[dilbert]

Hi all,

10 days ago, I have set up a new 15 gallons tank.

It's about 16 lbs Fiji cured live rock in there that I bought personally from two different LFS and always drove it home within half an hour.

There is a thin sand bed of coral sand round the rocks.

Ammonia is 0 since a week (initially 0.50 then 0.25 ppm)
Nitrite 0
Nitrates 0 (a week ago, not measured since then)
KH 8 - 10 (three different test kits ;-) )
Cu 0
ph 7.8 - 8.3
temp 25°C (78°C)

Water is RO from the LFS, sea salt is no name from the same LFS that uses this sea salt himself. I have used this sea salt already in my brackish because it dissolves very well and keeps the ph stable. (Another salt went to ph 9.0 to fall then within a day to 8.1.)

I use two powerheads Maxi-Jet MJ-500 with 480 l/h and no further filtering system.


Now, I face the problem that my ph goes always down about afigure of 0.2 or 0.3 a day and I have to add Seachem's Liquid Marine Buffer at the full recommended strength of 3 caps (1 cap for 20 liters, 60 liters ~ 15 gallons).

I presume it's excessive CO2 as the house has double-glazed PVC windows and gas central heating with an additional open gas fire in the living room which now much in use.

I haven't done a water change yet. I only added some kalkwasser just to see how it works. But I guess those measures won't have an impact for long.

Does it mean I have to look out for a cheap source of this "Liquid Marine Buffer" then?
:eek3:

[Grins]

That is a respectable range of pH, especially with no natural air in the room. I'd not stress about it too much.

[dilbert]

So, you think, too, that it's the air in the room that causes those ph droppings?

Only with this rate of dropping I would need to do a daily water change or constantly add this stuff from Seachem.

Is there no other solution?

[Grins]

I think it is a probable culprit, however I'd suggest giving this a read: http://reefkeeping.com/issues/2007-05/rhf/index.php

[dilbert]

Thanks for that link. Very useful.

[dolfans1]

What is your SG and alkalinity?

Generally, the higher the alkalinity, the less swing in pH you will see. Similarly, the higher the SG, the less pH swing, as the additional salt acts as a buffer.

When I was teaching undergraduate chemistry labs in graduate school, students always used to ask me "What can you ever do with chemistry?" Ha! Set up marine aquariums and brew good beer! What else do you need?

[dilbert]

I try to have my SG at 1.025.

I got already an alkalinity test but I don't have the figure in mind anymore. I measured it about a week ago.

But I know now the route to go. I got a carbondioxide infested room, I bought this "Liquid Marine Buffer", and I bought kalkwasser to really use with caution as I found out (the ph sky-rockets with this stuff :grinyes:).

I also got a digital handheld ph meter that is low-end quality but always matches at least the liquid ph tests I got, too. So, it's not too much of a hassle to constantly monitor the ph value.

BTW, I got the same problem in our brackish tank with same size in another room, too. Since we use more heating and additionally I had the splendid idea to install an airstone ... :headshake2:, ph went down like crazy what it has done never before.

[dolfans1]

When adding kalkwasser, it's best to do it at night if you're not already doing do, when the water pH tends to drop due to respiration of the photosynthetic organisms (they emit CO2 at night, which is why the pH tends to drop). This helps offset the pH effects of the kalkwasser. Also, add it slowly. 1 drop per second is probably a good rule of thumb to avoid fast changes in pH.