Tap pH different from tank pH and Water Changes

WaterBaby

WaterBaby

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Sep 23, 2002
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What do you do when your tap pH is different from your tank pH. I have never had this problem with any of my other tanks before. All my other tanks have a pH of 7.6-7.8. My new setup is different.

I have a 29g set up for about 2 months. It has a Flourite substrate and is lightly planted. I cycled it with Bio Spira and squeezings from another tank. I have cycled other tanks and never had a pH so low in any of them. Is it from the substrate, plants? This is my only tank with Flourite and my only tank with this many plants.

Parameters are:

pH- 6.4 to 6.6
No Ammonia, Nitrites
Nitrates are 5ppm or lower


My tap water comes out at 7.6 to 7.8. I age the tap water for a few days first and then treat it. Should I be concerned when I do a water change of about 20%? I really don't want to start messing around with the pH in the change water.

Inhabitants are:

1 Dwarf Gourami
4 Scissortails
2 Lemon Tetras
5 Neons

I don't do any other testing in my tanks other than for the above things.

Michele
 
Flourite is supposed to be completely inert, and SeaChem specifically says that it will not alter the pH of the tank.

Plants will generally drop pH a bit, as will stuff like driftwood and some rock, but with rock it's more likely that it would increase pH, not lower it. The primary culprit is probably the plants.

You could toss a bit if crushed coral into the filter, that would return you to a bit higher readings, if not as high as that tap water. If you can get the tank up to within .5 of being the same as the tap water, then a 20% water change would result in a .1 change in tank pH when you do a change. The fish should handle that OK.

Right now, you are looking at a difference of 1.0, meaning that the tank water is 100 times more acidic than the tap water, and a 20% change is increasing the pH in the tank by .2 in a short period of time. That's a bit much for me...

Normally, I would say that a low pH that is stable is better than a fluctuating pH so leave it alone... But since you have that much difference between tank and source water, I feel that in your case this rule doesn't apply. Others may disagree, this is just my opinion.
 
I do pretty much agree with you on this one CaptnDan except for one this. I would not add anything to the filter but add it to the water as it is aging. In this way there will be the same pram water going into the tank versus putting low pH water in and rasing it from within the tank. Basicly do what CaptnDan says but don't add it to the filter. This will cause the pH in the tank to rise and it may rise to much. Add it to the bucket or whatever you are keeping the aged water in. Test it before adding it to the tank and make any adjustmemts as needed. If the pH is to high in the aged water simply add some normal tap water to bring it down a bit then add it to the tank.
 
Plants actually increase & stabilize pH. Not the other way round.

The lower pH is probably just from the nitrification process, which uses up alkalinty.

It's not realistic to think that the tap water pH and tank pH will remain the same.


There is no need to mess with the pH chemically or with crushed coral.

Just perform a couple of 20% water changes and the pH will be back up.

Adding more plants may also help.
 
do u add co2 for the plants?
 
No, no co2 for the plants

What if I floated a "peat pillow" in the change water for a few days. Would it bring the pH down a little? Actually I'd rather lower the pH of the change water than raise the pH of the tank (without using any chemicals).

How would adding more plants help?

Michele
 
Needeles said:
If the pH is to high in the aged water simply add some normal tap water to bring it down a bit then add it to the tank.
Click to expand...

I had thought the same thing at first, but the problem is that the pH of the tap water is already higher than the tap water.

I figured the path of least resistance would be to increase the tank pH, since it's easier (to me) to raise pH than to lower it. That and I am sure that my thinking was influenced by the fact that I don't have to age water before using it - I can use it straight from the tap.

Either way, seems we definitely agree that changing with water that's up to 12 points different is not a very good thing. Nice to know I'm thinking somewhat straight. LOL
 
So,,, what have we decided...

adjust the tank water, or adjust the change water? And how?

I have done a few minor water changes in the tank (and not killed anyone), and the pH remains at that mid 6 range. It's like the tank converts the pH of the tap to its own level.

Michele
 
Sorry that nothing specific jumps to mind. Just feel like we are missing something.

Did not see a response from you on if you are using CO2..?

What specific, if any ferts, liquid or solid?

Any specific decor, like type of rocks, driftwood (especially if it is really old and decaying)..?

Was this a tank that was used by someone else (contaminate leaching from silicone) or new? Ever repaired (improper silicone)?

I'd be interested in seeing GH/KH on your tap, other tanks and this tank.

What kind of filtration and media are you using on this tank and in comparison to the other tanks (plastic, ceramics, shell, beads, carbon)..?
 
Is this the same 29 gal tank as this other thread you posted?

http://www.aquariacentral.com/forums/showthread.php?t=83284

What did you use to decontaminate that tank? You note in that thread that the pH was 7.4.

If the same tank and it use to have a 7.4 pH and now it runs in the 6's, I would think whatever you decontaminated the tank with is leaking back out of the silicone.

Just a thought....not sure...
 
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