help understanding GH and KH pls

[Coyne]

Tanks been fish-less cycling for about a week now and I wanted to test the GH and KH of the water to see if the rock I put in is doing anything strange.
The results were GH 11 and KH 20... same as my 45gal community tank that doesnt have rocks (other than the gravel).
The KH seems super high to me. The API chart doesnt even go that high. Is this going to be a problem for a crayfish? Online research says the KH should be between 3-10. Could I be doing the test wrong? Seems pretty straight forward to me, but you never know.
PH is 8.2, if thats helpful to know. This is normal for my area.

I honestly dont even fully understand GH and KH... so some explaination of that would be helpful too.

 

[aluka]

you first have to see what is the unit of measurement you are using. Most testing kit measures in ppm, but when people talk about gh, its in dGH. Like when we say cherries should be in 4-10 gh, that is dgh.

for example, my water test to have kh of 35 ppm. to get to dKH, you divide ppm by 17.86.
so my water had a kh of ~ 2 dKH.

 

[Coyne]

I believe it's dGh and dKh. It it helps, the numbers in my original post were the number of drops it took to make the water in the vials change color.

 

[Fidgetromeo]

Pretty sure the number of drops gives it in dkh and dgh... Unless I've been doing it wrong too

 

[spiketooth]

each drop is 1 dkh. Same with gh, so 20 dkh would be really high

 

[Coyne]

Agreed... It's why I'm trying to understand it.

 

[aluka]

ah, it seems we use different testing kits.

Yes 20 dkh is really high. Is that the same as your tap water? if its different from your tap water, then something in your tank is leeching.

If your tap does come out with 20 kh and 10 gh, then you can consider mixing your tap water with ro water to lower the amounts. Most supermarket sells ro water for about 0.80/gallon. or if you use their water dispenser, they are 0.35/gallon.

 

[Coyne]

yes.. Tap is the same. Apparently I just live in an area with high mineral content and high PH (I guess theyre related).

Ive done more research since my original posting and have learned more about what these two things are and how they relate to a fish's health. Im not as worried about it as I was before. Turns out that too high, while not ideal, is still better than too low. My fish are seemingly doing fine, though Im not sure how the crayfish I plan on purchasing in the next month will be affected.

 

[aluka]

fish are extremely tolerant. Shrimps and crayfish on the other hand are more sensitive to the water content. Because they pull minerals from the water to build their shell, so they can molt. Too high or to low gh/kh will cause them to have molting issues and die.

 

[Coyne]

hmm.. any idea how high is too high?
My Kh being super high and my Gh being average leads me to think that the majority of the mineral content in my water is calcium, which is what shellfish pull from the water (and food) in order to regrow their shells. On the surface this seems good, but Im guessing maybe theres a flip side.

Would it be smarter to put some shrimp in there first and see how they fair?

 

[aluka]

neo (cherries) being the most hardy shrimp, needs to live under gh 14. I am not sure about crayfish. =/

 

[Coyne]

I guess that's good news.