The Planted Tank Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
184 Posts
Discussion Starter · #1 ·
I use the API GH and KH liquid test kit, and the instructions say to add one drop at a time and cap the test tube, shaking it between each drop. Do you actually have to add one drop at a time if you know your water will be around a certain level? For example, my water is pretty hard and I have a GH of about 10, so could I add 7 or so drops at first to so that I don't have to do each one individually? It is still the same ratio, so it won't matter right?
 

·
Registered
Joined
·
1,916 Posts
I use the API GH and KH liquid test kit, and the instructions say to add one drop at a time and cap the test tube, shaking it between each drop. Do you actually have to add one drop at a time if you know your water will be around a certain level? For example, my water is pretty hard and I have a GH of about 10, so could I add 7 or so drops at first to so that I don't have to do each one individually? It is still the same ratio, so it won't matter right?
I think you'd be ok doing that. The only problem I can foresee is if you get the color change after adding 7 drops and shaking. Then you dont really know if it took 7 drops or maybe only 6 or even less. i dont use the gh and kh test often so its been a while; but I think you can see the color change as soon as the last necessary drop hits the water anyway.

On a similar idea; I do always wonder about any of the tests that require the 2 different re-agents like nitrate. Is it necessary to cap and shake after using the first and before the second?
 

·
Registered
Joined
·
11,721 Posts
I do that (add several drops then shake) for the GH and KH tests.

When using a 2-reagent test I do shake in between. Some instructions tell you to shake and for how long, others just sort of show a picture of the test tube being turned upside down, like it is just a little shaking. Better if it is well mixed!

Other ways to alter the tests:

If you know a test will read really high (such as NO3) but you cannot read the colors, or it is off the chart, you can dilute the sample with RO or distilled water. For example, instead of 5ml aquarium water, use 1ml aquarium water + 4ml of RO. Then multiply the result by 5.

Another way: Some of the tests have you add a LOT of drops, and it is an even number of drops.
I just take half as much of a sample, then use half as many drops. Same ratio, right? Same results. Get twice as many tests out of one kit.
I would not go less than half a test tube, though. It might get tricky to see the color if there is a smaller volume. I read these tests from the side. If there is some strong color nearby the test tube might pick it up and the color in the tube might look 'off'.

Another way: I generally use the tests to compare how the tank is going over time, not to see if a particular parameter is some perfect number. To do the GH and KH tests, I can get a rough idea if something is changing by stretching the drops out. I will fill the tube only half way, then count drops like this:
1 drop = 2 degrees
2 drops = 4 degrees
3 drops = 6 degrees
This uses less reagent and confirms that things are just fine, as long as it is the same as before. And if there is a problem, I can always re-test with a full test tube and then 1 drop = 1 degree.
 

·
Registered
Joined
·
184 Posts
Discussion Starter · #4 ·
Thanks so much guys! Both answers are awesome, detailed, and really helpful!
 
1 - 4 of 4 Posts
Top