KH and GH results

I just bought an API test kit for GH and KH and I'm a bit confused regarding the results. For the GH it said to use one drop at a time till the water turned from orange to green. This took 10 drops. If I'm reading the directions correctly, according to the conversion chart this gives me 179 ppm GH.

For KH the instructions states to add drops till the water turns from blue to yellow. The water was never blue, it was basically a light yellow at the first drop. According to the chart this would be 17.0 ppm KH.

I really have never monitored the GH/KH of my water so I have no idea if these results make sense. Could GH be that high and KH that low? My pH out of the faucet is 7. My tank is a 75, heavily planted, with a decent load of fish and the pH tends to stay at 7. I only do small monthly water changes so it's not staying at 7 because I do changes, it seems to be buffered rather well. Ammonia is at 0, nitrite 0, and nitrate ~10.

Any thoughts on the hardness results?

 

KH is usually lower than GH, but the fact that the KH is that low is cause for concern, as pH tends to fluctuate a lot with a low KH. CindiL can help.

 

That's kind of why I think the test may be defective. My pH tends to be rock solid at 7 - 7.2.

 

Did you shake the test tube after adding the first drop of KH test?

 

I tried again. I first tested my water out of the faucet and it read 3. I then tested the water from the aquarium and got my previous reading, the water was yellow at the first drop. And yes, I shook the test tube well. So it seems the test is working as it read KH in my tap water. The KH is dropping to almost nothing in my tank.

I'm not well versed on water hardness so I don't know what to make of that. My substrate is all Eco Complete. I have two pieces of driftwood (bought from aquarium shops), and the tank is heavily planted. I'm also using Seachem Flourish and Excel along with plant tabs in the substrate.

Is this an indication I need to do more water changes? I keep them at a minimum as the tank is so heavily planted and I monitor the ammonia, nitrite, and nitrate every couple of days and it's always the same, 0, 0, and ~10, respectively.

Thanks for the input.

 

Hi, that is low and would make me nervous if that was my tank. My guess is that your plants are consuming most of the ammonia and you are probably not over stocked. That is a precarious balance though because at a dKh of 1 in the tank, it wouldn't take too much to crash your ph and wake up to a tank full of sick or worse fish. But on the other hand if this is the tank that has been setup since 1992 in your profile? or is this a new tank? I think at a minimum I would add a small amount of coral or aragonite to your filter or substrate so that if the ph ever starts falling the coral will dissolve and help hold it. Ideally your dKh would be above 3 at all times. 5 would be better. You could buffer it with Seachems Alkaline and Acid buffers but again if this tank has been going for years with no issues then the coral may be enough since it is so heavily planted.

 

I tore down the old 29 that I had since the early 90s an replaced it with this 75 about one month ago. I used the old filters (one HOB and one powerhead with sponge) to get it cycled along with the cycled canister that came with the used 75. Everything went quite well. Fish and plants seem to be doing great and the water parameters (with the exception of the KH of which I never used to check) are fine.

I'm about to open the canister today to add some Matrix and Purigen. I can pick up some crushed coral to add at the same time. How much would you recommend? I don't want to end up with African Cichlid type conditions.

 

Maybe just start with 1/2-1 cup and go from there based on any results you may see (which will take a few days). Just start with 1/2 cup and see if there is much of a change at all in that size tank (with your ph).

 

I went out today to my LFS and bought a 10# bag of crushed coral. I put 1/2 cup in a bag and placed it in the top tray of my canister filter. I also replaced the existing ceramic rings in the third tray with Seachem Matrix (nothing to do with the KH, I've just been meaning to do that).

I'll monitor the KH and pH daily for changes. If I don't see a change in KH by Wed should I add another 1/2 cup or should I give it more time? I'm not sure how long it should take to change the hardness in a 75 gallon.

 

I'd probably add more if you don't see much by Wednesday since it is a large tank.

 

As of yesterday I saw no change in KH so I added about 3/4 cup more crushed coral to the filter. As of today there was still 0 KH. I'll keep checking and if Saturday I don't see a change I'll add another 1/2 cup. I hope it comes up soon, this filter is heavy...

 

You could always use Seachem's Alkaline and Acid buffers together. The alkaline buffer will bring up the kh with a couple of teaspoons and the acid buffer lets you get it closer to your tap ph.

 

Yesterday I noticed the KH was now up to 2 degrees and the GH staying steady at 11 degrees, pH still at 7. So it seems to be working. I'll continue monitoring the KH, if it doesn't increase I'll add another 1/2 cup of crushed coral in a few days.

I like the thought of using the crushed coral over adding the Seachem chemicals as I feel the coral will, in the long run, be more stable as it will stay in the filter and do it's thing (once I get the right amount in there). Water changes will constantly be taking the Seachem chemicals out of the water and I will have to continually re-add them. At least that's my opinion.

 

How about mixing in some aragonite sand? It will do the same thing in small quantities and you won't have to put it into your filter. The crushed coral can also be mixed into your substrate. It doesn't have to go into the filter.

 

I really like the look of the Eco Complete as it is, mixing crushed coral or sand with it, in my opinion, would make it less aesthetic looking. As long as adding it to the filter does nothing negative to the tank I would prefer to keep it there, out of sight.

I'm hoping that once I get the KH where it needs to be I can stop messing around with the filter anyway, at least that's my hope. I certainly appreciate all the advice you've given me. So far it seems to be working, slowly but surely.