KH&GH question

[Vineheart01]

Hi, so i am creating a live aquarium and currently in the stabilization stage prior to adding the plants.

Its a 75gal tank, aiming for a 6.8-7PH (which my last stick test showed i was in that ballpark), sitting at around 78F. Its going to have redtailed sharks, pearl gourumis, congo tetras, and a pleco in there eventually (and if i feel like im not overcrowding i'll grab some swordtails).

In the past when i had fish tanks i never really paid attention to anything on the test stick except the pH. Since this tank is rather involved im trying to do it right, and the GH and KH are really high so im concerned thats actually a problem. From what im finding it seems the KH might be fine since i see a lot of "live bearers may prefer higher than 140ppm" comments, but GH concerns me....
KH sits around 180ppm and GH i think is off the chart (180ppm is the highest it goes).
GH is a very noticeably purple color, but the chart doesnt include that shade, just a deep blue that has a hint of purple for its highest value.
The test strips are API 5 in 1 test strips.

Should i be worried about that? and what should i do if i do need to adjust that?

 

[Andy Sager]

What that means is that you have hard water vs soft water. It's actually a little suspicious that your pH is as low as it is. Usually hard water has a higher pH. Over time, the general consensus has circled back to " It's better keeping fish that like your water parameters rather than trying to chase a parameter that is going to constantly change due to your other parameters." ( This was a popular consensus back in the 60s but somehow we moved away from it. ) Your higher KH is what will be making your pH want to go higher so the work around for that is to use RO water or RO water mixed with your source water to lower the KH level. ( The old work around for that was to use rain water or a rain water mixed with your water or filtering water through peat moss. Can you tell I was around back then. LOL )
So you may want to rethink your stock list and get plants, as well as fish, that will do better in your water parameters as well.
For what it's worth, liquid tests tend to be more accurate than the test strips. Fritz Aquatics has a good master kit as well as API.

 

[Vineheart01]

pH is that low because i put pH down in there, it was almost 8.
I did a little more digging and found that im probably too hard for Congo Tetras right now but the rest should be fine, so i probably need to replace some of the water with softer water to balance it out.

Did another test just now and i think its just my eyes messing with me making that GH test look purple. pH remains about ~7

 

[Andy Sager]

pH is that low because i put pH down in there, it was almost 8.
I did a little more digging and found that im probably too hard for Congo Tetras right now but the rest should be fine, so i probably need to replace some of the water with softer water to balance it out.

Did another test just now and i think its just my eyes messing with me making that GH test look purple. pH remains about ~7

That sounds better. It's the KH unfortunately that controls the stability of pH so that is what you need to keep track of and adjust more than the GH.