Confused About How To Read Dh Test?

[lillykinloo]

Hi everyone! I tested the dH levels in my aquarium water today, and I am a bit confused about how to do the test and what the results mean. I have the Tetra dH test kit. According to the directions, I'm supposed to collect 5 ccs of water & then count the number of drops of test solution it takes to turn from red to green. This is a bit difficult, because I have a piece of mopani wood & a piece of bogwood in my aquarium. Despite boiling the bogwood twice & soaking the mopani wood in my bathtub for 4 nights, I still have quite a bit of tannins in my water. As a result, the color of the test solution seems to be a bit distorted since I'm not dealing with crystal clear water. From what I could tell, the drops were no longer orangish-brown on the 6th or 7th drop. I tested my tap water just to be sure. With my tap water, the drops were no longer orangish on the 7th or 8th drop. Am I doing this test correctly, or am I supposed to keep adding drops until the water turns completely green? At 6-7 drops, the aquarium water was still brownish with a green tint. Also, what does 6-7 dH mean? Is this soft or hard water? There wasn't really a good explanation of test results in my instruction booklet (it just said most aquarium freshwater fish prefer 6-16 dH). Thanks again!

 

[Majjie]

Hi Lilly

I'm not sure I can fully answer your question - I'm not familiar with the Tetra test.

There are two sorts of hardness: GH or general hardness and KH or carbonate hardness. Both are calculated as mg CaCO3/litre or (if multiplied by 0.056) as degrees of hardness or dH. Does your test kit say whether it is testing for GH or KH? (CaCO3 is calcium carbonate - in case your chemistry isn't too hot )

In my test kit - which is a Nutrafin one - there are two different test solutions - one for each test. And when you get the number of drops you have to multiply that by different numbers to get the CaCO3mg/l and then by 0.056 to get the dH. Yours could well be different though.

It's very difficult to change the GH of water - so most people don't bother. It's also quite difficult to change the KH and keep it stable - because KH is related to pH.
It's quite useful to know how hard your water is though - so that you know which fish will be happiest.

 

[lillykinloo]

Hi Lilly

I'm not sure I can fully answer your question - I'm not familiar with the Tetra test.

There are two sorts of hardness: GH or general hardness and KH or carbonate hardness. Both are calculated as mg CaCO3/litre or (if multiplied by 0.056) as degrees of hardness or dH. Does your test kit say whether it is testing for GH or KH? (CaCO3 is calcium carbonate - in case your chemistry isn't too hot )

In my test kit - which is a Nutrafin one - there are two different test solutions - one for each test. And when you get the number of drops you have to multiply that by different numbers to get the CaCO3mg/l and then by 0.056 to get the dH. Yours could well be different though.

It's very difficult to change the GH of water - so most people don't bother. It's also quite difficult to change the KH and keep it stable - because KH is related to pH.
It's quite useful to know how hard your water is though - so that you know which fish will be happiest.

Thank you very much for your reply, Majjie! The Tetra test that I have only tests for GH. If I read the instructions correctly, my test results would indicate that my aquarium water is at 6-7 degrees of hardness/GH. But, I'm not quite sure if this means my water is soft or hard? Thanks again!

 

[Majjie]

Sorry Lilly - forgot about that part of your question. 6-7 dGH is about medium I'd say - not particularly soft and not particularly hard