Tap Water Question: high pH and low GH/kH...what gives?

[jowens]

Hi guys,

I just moved. In my last apartment, my tap water was very hard and basic. When I arrived at my new apartment, I took the lazy route, only testing my tap water for pH and not hardness. When I saw the pale blue, I thought, greeeeat more hard water. Then I did a large water change on my tank.

Weeeell, let's just say the fish acted a little funny. No one died, but it was clear that something a little strange was going on. The next day I checked my tank's pH and it was pretty low (for this tank) - around 6.6. Confusion ensued.

To make a long story short, I checked the GH and kH for the tap and found them both to be very low - around 2 degrees GH. The strange part is that the pH of the tap is quite high. Can anyone explain this? As an experiment, I left a pitcher of tap water over night to see if the pH dropped - nope, still high this morning. So then I added a single drop of "pH down" to the pitcher, to see if that caused a sustained drop in pH. We'll see what that did this afternoon.

Ironic as it may seem, my RO Unit arrived in the mail this week as well (doh!). So...just as I'm starting to figure out how to use the thing, now it turns out I have soft tap water!!!!

At any rate, I'm new to this stuff. Any advice or stories out there to help me along? As neat as the RO Unit is, let's face it: it's a pain to set up and use. If my tap water is going to soft, shouldn't I just use that?

Incidentally, I'm in the Quincy, Massachusetts area (10 miles south of Boston)...so if anyone's from that area, please advise.

Thanks,
Jason

 

[Neil]

jowens,
You're just trying to torture us, aren't you!
I'm not going to shed too many tears for you! :cry: As I see it you've died and went to Dwarf Cichlid heaven.
You didn't say how high your pH is, but if your tank is 6.6 than I would say it isn't going to be an issue. The pH should be easy to deal with and the hardness is perfect. You can put away your RO unit and use it if you deal with a fish that absolutely requires less than 1 degree hardness like D. filamentosa, etc.
You probably will need to be a little bit more careful about pH crashes, but there is enough buffering in your tap to make that not too much of a problem. LOL and have fun with your new-found RO tap supply. :lol:
Neil

 

[farm41]

I am contemplating getting an RO, maybe you don't need yours. What did you buy and do you want to get rid of it?

 

[jowens]

Thanks Neal. I'm going to contact the water company and find out if they're using calcium or a disolved gas in their treatment processes. Neither would necessarily show up on a standard pH or GH/kH kit and each could effect pH. If it's a gas, simply running an airstone would theoretically eliminate the problem. The pH coming out of the tap is about 7.4.

The reason I'm a little hung up on it is because I use CO2 injection. I actually haven't initiated it on the tank yet since I moved, but it's helpful to feel confident about the water before turning it on. I want my pH to be about 6.6 in my main tank, and to do this, I need a kH of 3 (which, without CO2 injection, results in a pH of about 7.6). But with the pH being so high, it's just got me a little jumpy, you know?

Farm, here's the RO Unit I got:

http://www.aquaticreefsystems.com/3_Stage_Reverse_Osmosis.htm

It's an extremely sturdy piece of equipment built especially for fish tanks. You can get them for cheaper, but since I have to hook mine up to the kitchen sink, I wanted a 50 gpd unit...so I could get a water change's worth over the course of a single night's sleep. I'm going to hold onto mine for now, but if I can get a bit more confident, maybe I'll want to get rid of it. The only thing is, I've only used it twice, so I wouldn't be able to slash the price that much! At any rate, I recommend this RO Unit from my limited experience. I've spoken to the owner of the company, Brian, a couple of times by phone when I had questioned.

 

[Neil]

farm41,
One of the members here, Mike Chappell, offers RO units through his website. http://www.threeguysaquatics.com/productList.asp?prodCat=21a&catID=21 He might also be one to talk to about what is best to suit your needs.

jowens,
The issue of CO2 injection into your tank does complicate things a little. As far as I know, KH combined with a specific amount of CO2 will derive a particular pH. So maybe you can alter the amount of CO2 injection slightly to get the desired results. I am pretty sure that 2 degrees is enough hardness to control this process. However, this is far from my strongest area, so maybe someone with a little more solid info can chime in. Good luck, Neil

 

[jowens]

Neil,

I've had some good results. I hardened my tap water to about 3.5 degrees kH and began injecting CO2 at a rate of about a bubble every 1.5 seconds, shooting them direcly into my Eheim canister filter. The resultant pH has been about 6.7 (which means my dissolved CO2 level is a healthy 20 ppm).

There are two ways to control pH now. I can either harden/soften the water more or I can increase/decrease the CO2 injection rate. It's really not very difficult to do once you get the hang of it. Actually, in the end I think I have more control over pH then before. This (according to my theory) is because the carbonic acid being released by the CO2 keeps the pH levels "honest." What I mean is, without the carbonic acid, pH has a tendency to fluxuate upwards a bit. With the acid holding it down, however, you're pretty much garanteed that the pH will always be at the absolute bottom level corresponding to the tank's kH. Simply put, as long as I keep the kH and bubble rates constant, I will have zero pH fluxuations. Of course, I'm just getting into it, so I could be wrong.

Down the road, I want to soften my water a bit and reduce the CO2 level just a bit, down to about 15 ppm. Which actually brings me to another question: for stubborn breeding Apistos like Agassizii, what's more important - low pH or softness? In my tank, for instance, the pH will be quite low...but there will always be a little bit of hardness. I don't really understand conductivity at all.