High PH in Soft Water conditions???

[Mick John]

G'day everyone. This is my first Thread and would like to say Hi to everyone. I have a problem with my 500 Lt tank. It's about 3 Months old and the PH wants to keep rising past 8.00! The tap water is naturally neutral and I filter this through a Carbon Filter etc.. It has no GH or KH. During the initial stages of setting up the tank I added Aquadur which acts as a Buffer. At this point the GH was about 6-8 degrees Hardness. I began introducing CO2 which is regulated by a Sera Ceramic. The reactor is a Dupla suitable for up to a 2000Lt tank which is situated in the Sump. I have Discus, plants etc. and set the PH to 6.8. In order to achieve this I have had to go through a 2Kg Bottle of CO2 a week just to do this! The KH is 4 and the GH is about 4-5 so what's Buffering the water to this extent I am unsure of. I have tested the Substrate for Calcium and nothing. I use Morena which is a Peat Extract and no effect. I now have a bag of Peat in the Sump which also contains 2Kg of Siporax, sponges and the CO2 Reactor. Prior to the Sump the water trickles through 1KG of Siprax before falling through the PVC Piping. I have changed the old Probe and also tested the water with a JBL Test Kit and this just verifies the PH. Once the CO2 runs out the PH races back up and past 8.00!
Does anyone have any ideas. I thought that maybe the water was becoming that Oxygenated that it was pushing the PH up but I have consulted a couple of reliable sources and I have been told that Oxygen alone would not have that kind of significant effect on the PH. Nor would a CO2 deficiency caused by the filtration.
Does anyone have any ideas? I'd appreciate it.

[Woodsy]

Hey mate, and welcome to the forum ;)
What type of rocks do you have in there? Some rocks/substrate will raise the pH without containing calcium.

[Mick John]

Thanks for your response Woodsy http://www.thefishtank.com.au/forums/images/icons/icon7.gif . The problem is most of the Substrate I have used in my previous Tank without any complications. They are from a natural Creek in a nearby Rainforest in Cairns.The other rocks are few, (1 large and 2 small) from another Creek. Apart from the Calcium test I don't know much about them. But not sure if there are enough of them to create this kind of change. The rest of the Substrate is a very white powdery sand which my Mate sold me, 3mm black gravel and some local Laterite. All of which posed as no problem in the last set up. I noticed last night that the CO2 reading was quite high and the PH was a solid 7.7 . I thought about turning it off but I know what the result will be.I replaced the solution in the Test Chamber and will see what it says today. Besides, the Fish aren't showing any signs of stress and aren't gasping for oxygen etc.. Just funny how the water is (seemingly) saturated with CO2 and the PH is still high? http://www.thefishtank.com.au/forums/images/icons/icon5.gifIf the Test Kit was not verifying this PH reading I'd still be assuming that the Probe and the Regulator were playing up. But how reliable are these Test Kits anyway? I'll keep on monitoring it and see what I come up with. I'm hoping that as the System ages it will settle but this I think is probably wishful thinking eh.http://www.thefishtank.com.au/forums/images/icons/icon10.gif Cheers Mate.

[Woodsy]

Depending on your test kit, it may not measure total alkalinity, but carbonate alkalinity alone. There may be borates and magnesium in there, working to drive your pH up. Might pay to get a Seachem alkalinity test kit, and then you can get a much netter idea about what may be buffing your pH.

[Mick John]

Thanks for that Woodsy. I'll look into that. At the moment I'm very suspicious to a CO2 leak in the System. Getting it closer scrutinized tomorrow. Doesn't help when I have a trickle filter too. Trying to lower the GH naturally with peat and with the appropriate CO2 levels should be able to stabilize the PH to around 7.2-7.4 . Maybe a little lower over time. With a KH of about 2-3 it should give me a CO2 level of about 5-7 pmm. I'll keep you posted. Thanks again mate.

[Mick John]

Well it seems that the trickle filtration and possibly the Sump was the cause of the rise in PH despite the Soft water conditions. I placed a valve on the pump and restricted the flow by a third and introduced CO2 back into the water and what do you know, the PH dropped no problem and didn't rapidly increase again as there is not a mass amount of water being turned over and being oxygenated. And the CO2 levels will hold alot longer in the tank before falling into the Trickle Cycle.. Hopefully around 5-10 mg/l. Compromise is there is not a large amount of water being turned over now but due to the amount of Bio Media I have in the Filtration hopefully this won't pass as a problem. Touch wood I can now concentrate on other things now like trying to husband Discus Fry and keep them alive. The Discus are still young so the first lot of eggs they ate. Having no experience with this I was horrified when I saw the massacre.http://www.thefishtank.com.au/forums/images/icons/icon10.gif Then I was kindly informed that this is normal for the young Pair. Within a few days they have layed more eggs so I'm hopeful again. I've even left a night time light on for them.http://www.thefishtank.com.au/forums/images/icons/icon7.gif Cheers.

[Woodsy]

Glad to hear you were able to solve the problem mate. I would never have thought that DO would have had THAT much of a difference to the pH - You learn something new every day :p

[Mick John]

Oh dear. Time to confess I suppose. The PH was showing that it had dropped but later I discovered that the water restriction wasn't the main reason. It eventually dropped to around 6.4 and I was very happy but also suspiciously surprised. Well, after considering this I noticed the Probe had algae growing on it. I proceeded to clean the Probe and placed it back into the tank and O.M.G! PH of about 8.00! Again.http://www.thefishtank.com.au/forums/images/icons/icon10.gif Bloody algae! Anyway on a slightly brighter note I have found a leak in my CO2 Bottle so I'm now not going through 2Kg in a week! My friend still believes it's a combo. between the Syporax and the possible slight releasing of minerals from the Substrate. Even though the Substrate doesn't have a high concentration of these. Funny thing is the Tap water has a Kh of about 1-2 Degrees Hardness and the tank water has always maintained about 4-5. So something is causing this. But even so, it's still quite soft water. The Ph will even rise at night with the lights off. It's the CO2 that keeps it to around 7.4. I would like it lower but will then have too much of the gas in the water because of the naturally high PH. Frustrating. I'm told over time the PH should start to settle. Maybe years. Funny thing is I now have two pairs of Discus breeding in the Tank. They're not bothered by any of this.http://www.thefishtank.com.au/forums/images/icons/icon10.gif http://www.thefishtank.com.au/forums/images/icons/icon7.gif