KH, CO2, and pH

[CaptnIgnit]

So I finally got my CO2 kit and my KH testing kit last night. I took some readings before hand and hooked the CO2 up. I do have a few question for those chemistry guru's out there.

First, here are my read outs for my tank and tap water:

Tank water - KH: 4 degree's, pH: 7.9
Tap water - KH: 2 degree's, pH: 7.7 (straight out of the tap, will do a test with water that has sat out for 24 hours later)

My main question is, with the two degree difference, will doing PWC's cause too much of an affect on my fish and plants?

Also, I'm not sure what is causing my pH to be so high, but I assume that with the CO2 starting to get mixed in it should drop it down to a resonable level. Although, If it were to stay up high for any reason, would it affect many plants or could they deal with the high pH?

 

[rich311k]

The plants won't mind that KH, if the PH doesn't drop then your CO2 is not working. The KH difference is minimal if you did a 50% water it would drop less than 1 degree nothing to worry about.

 

[czcz]

I think it's a good idea to isolate why KH went up, then address it. It could be from something as simple as top-offs instead of water changes for an extended period of time.

To add to Rich's post, if you have sensitive fish you could gradually lower KH with a bunch of small water changes, then the 50% water changes weekly should keep it stable.

If it's DIY CO2, sometimes it takes a day to get going.

 

[CaptnIgnit]

Thanks For all the replies.

I assume the increased KH came from either my substrate (eco complete) or some of the rocks I have added (more likely). They are pieces of slate, most are a red color but a few are black/gray.

In any fashion, I'm not too worried about the KH being at 4 (infact I actually prefer it at 4 vs 2). My primary concern is just doing water changes and not hurting the fish/plants. I'll keep testing it and make sure it is stable at 4. after that I'll probably do a PWC and see how much it affects it and how long it takes to return to 4.

I do have a piece of bog wood in the tank, which makes me a little confused as to why the pH would increase while in the tank. But I guess I can't be too paranoid as long as it remains stable.

 

[czcz]

If the Eco or rocks are buffering the water and you want it, your plan is good. If its the Eco, it'll probably wear off eventually (likely after months), at which point you could choose to buffer the tap if wanted.

Since KH is higher in the tank, pH will be too, even with the same CO2. As Rich said, your pH should be lower though. If the CO2 is outputting gas, minimize surface turbulation, consider a better diffusor, and so on. If it is DIY CO2, its a good idea to regularly test to get an idea of howoutput changes.

HTH