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pH Issues in Zeb Tank

Posted: Tue Nov 10, 2009 9:35 pm
by Linzi Zeb
Hi,

I was hoping for some advice on my zebra tank. I have a 125 litre tank with 7 zebs in. 3 are 5-7cm and four are juveniles. I have a sand substrate and no live plants at the moment due to low lighting.

The readings are as follows:

pH 6.6

GH 5-6

KH 0-2

Nitrites 0

Ammonia 0

Nitrates 0-5

The reason I am concerned is that a couple of days ago I had a pH crash (i'm guessing due to the low KH). My tank water is pH 7.6 so i did have bogwood in the tank, which successfully lowered the pH to 6.6. I have since remove it in case this caused the crash.

The pH has since stabilised but I know that once my next water change comes around the pH will most likely rise. Is there anything I could do which would simultaneously keep the tap water pH lower than 7.6 while simultaneously increasing KH?

I was thinking re-adding the bogwood and I've heard that crushed coral increases KH but also the pH...

Any help you could provide would be greatly appreciated!!

Thanks in advance,

Linzi

Posted: Wed Nov 11, 2009 4:36 pm
by TwoTankAmin
Crushed coral will raise kh in smaller amounts as the amount increases it will also effect pH. I used to use it in my high tech planted tank into which I injected co2 which will act to lower pH. I was working to raise my kh some. The problem is that you will also be increasing your GH and will also have the net result of your pH being held higher.
Hardening Your Water (Raising GH and/or KH)
The following measurements are approximate; use a test kit to verify you've achieved the intended results. Note that if your water is extremely soft to begin with (1 degree KH or less), you may get a drastic change in pH as the buffer is added.
To raise both GH and KH simultaneously, add calcium carbonate (CaCO3). 1/2 teaspoon per 100 liters of water will increase both the KH and GH by about 1-2 dH. Alternatively, add some sea shells, coral, limestone, marble chips, etc. to your filter.

To raise the KH without raising the GH, add sodium bicarbonate (NaHCO3), commonly known as baking soda. 1/2 teaspoon per 100 Liters raises the KH by about 1 dH. Sodium bicarbonate drives the pH towards an equilibrium value of 8.2.

Raising and Lowering pH
One can raise or lower pH by adding chemicals. Because of buffering, however, the process is difficult to get right. Increasing or decreasing the pH (in a stable way) actually involves changing the KH. The most common approach is to add a buffer (in the previous section) whose equilibrium holds the pH at the desired value.
From http://fins.actwin.com/aquariafaq.html

Posted: Wed Nov 11, 2009 5:29 pm
by Linzi Zeb
Thank you very much for the clarification, do you think it's worthwhile trying the Proper pH 6.5 stuff? Something about it does doesn't sit right with me but I have no justification for this!

I might just add the bogwood back in as surely this couldn't have caused the crash? I'm not sure how to proceed as the pH is right as is the GH it's just the KH seems like a bit of a time bomb!

Thanks for your help,

Linzi

Posted: Thu Nov 12, 2009 12:20 am
by TwoTankAmin
I should have noted that there is no reason not to keep your zebras at 7.6 pH. These fish are tolerant of a wide range or parameters, especially in terms of GH/TDS. Unlike many other fish, seasonal spawners from Brazil tend to thrive on change which stimulates them to spawn.

If you are worried about the wood dropping your pH too much, I would suggest you try adding about 1/2 cup of crushed coral in a bag in your filter. Be aware it will take a bit of time before it will raise your kh. if after a few weeks you have not notice and increase of a point or two, oncrease the amount by 1/4 cup and see if that does it. I had to add about 1/2 cup plus to a 50 which, due to decor, probably holds closer to 40 gals.

Posted: Thu Nov 12, 2009 12:43 pm
by Linzi Zeb
I'll give that a try and let you know how I get on.

Thank you very much for your help, I'm finding that I'm worrying more about little things with regards my zebra tank than I ever have before in any other tank!

Linzi

Posted: Thu Nov 12, 2009 8:47 pm
by Linzi Zeb
One other thing too that I have noticed...the tap water is pH 7.6 but the tank is 6.6 at highest. I am currently using playsand as my substrate, could this be lowering the pH as drastically? I also have a UV steriliser but the pH was lowering before I added this. Do you think it's worthwhile removing this substrate and buying some different sand? It's the only thing I can think of that would be having such an effect as the pH is still trying to drop despite the removal of the bogwood. Only a partial water change every couple of days is keeping the pH above 6.0.

I'll try to get some crushed coral into an external filter and see how that goes but any advice on the sand would be great.

Thanks again,

Linzi

Posted: Fri Nov 13, 2009 5:27 pm
by TwoTankAmin
You may have disolved gasses in your tap water. Try this before doing anything else:

Fill a glass or small pitcher with your tap water. Drop in an airstone and bubble it for an houre or so and then test the pH. If you dont have an airstone and airpump, then let it sit overnight and test it the next day. These methods will allow for outgassing and results in a more accurate reading of your tap pH.

I would note I have this problem in reverse from disolved co2 in my well water. Out of the tanp I am pH 6.3, after outgassing I am pH 7.4.

Posted: Sun Nov 15, 2009 5:11 pm
by Linzi Zeb
Hi,

I have tried running an air stone in some tap water and it didn't alter the pH, it stayed at 7.6.

I have now added an eheim 2073 external filter to the tank, which had been cycling in the big tank in preparation. I don't know if it's coincidence but the pH has settled at 6.6 and hasn't moved for two days now. The KH is still 0-2 so I've acquired some crushed coral and will add that to the filter in a little while, once the filter has been running for a few days.

Thank you very much for your help and hopefully the coral will do the job, I'll keep you informed!

Thank you once again,

Linzi Zeb :)

Posted: Mon Nov 23, 2009 10:35 pm
by Linzi Zeb
Hi again,

I have reintroduced the bogwood and have added crushed coral to the tank and all seems well. The pH has been settled at pH 6.6 since my last post so hopefully that's the end of the problem. I'm hoping the coral will now harden the water slightly so I can get a good night's sleep again!!

Thank you very much for your help,

Linzi :D