Why is my water so hard?

[evojoey]

I have been trying to figure out why the water in my Geo tank is so hard. The Red Heads have lost a lot of color and I'm wondering if it's from the hardness. I tested both my tap water and my tank water. In the tank is silica sand, a couple pieces of mangrove root, 2 pieces of flat flagstone and a few live plants. Here are the water test results. Any help is much appreciated.

Tap Water Tank water
GH = 30 GH = 180
KH = 80 KH = 180
PH = 7.0 PH = 7.5

 

[peewee]

add driftwood and some sort of dry leaves. you'll know that's acidic when it turns tea colored

 

[OscarRobinson]

I'm guessing the flagstone. Try removing it before a water change and then check the parameters.

 

[Citrinellus]

I'm pretty sure silica sand doesn't have any effect on pH. I'm not sure about flagstone though.

 

[evojoey]

Thanks guys. I'll pull out the flagstone and do a w/c tomorrow then retest in a day or two. I hope that that's the problem.

 

[JK47]

Has the PH changed since you switched sand or is this a consistant reading? I have water almost identical to yours. Don't get sucked into the driftwood buffering down PH. It will soften the water to a degree but not by any significant measure. Have you considered using RO?

 

[IrnGynt]

Are either the mangrove root or flagstone new to the aquarium? I put some Mopani wood in my 29g and my GH and pH went way up.

 

[evojoey]

Has the PH changed since you switched sand or is this a consistant reading? I have water almost identical to yours. Don't get sucked into the driftwood buffering down PH. It will soften the water to a degree but not by any significant measure. Have you considered using RO?

The PH hasn't changed with the new sand, it's been consistantly around 7.5. I don't think the driftwood would soften the water enough to help me out anyway.

Are either the mangrove root or flagstone new to the aquarium? I put some Mopani wood in my 29g and my GH and pH went way up.

The whole setup is only a couple months old. I downsized from a 265gal. African tank to a 75gal. Geo tank. Everything in the tank has been in it from the beginning.(other than the new sand, which is the same stuff, just a finer grade) So this has been a constant problem.

 

[evojoey]

Well I found out why the water was so hard. I pulled the flagstone out and did a water change. I waited a few days to retest and the water tested way better. They're must be something in flagstone that was leaching into the water causing unneeded stress to my fish. Their color is already improving greatly and they are swimming around the tank a lot more. They're hungrier than before also. Thanks for the help guys.