Adjusting Kh And Gh?

I have a 29 gallon tank with 8 tiger barbs and 6 cory catfish.

My KH began at 9 dKH and my GH took 12 drops to change the water in the test tube from orange to green, which indicated it was at 214 ppm GH/KH (according to my API test kit).

This seemed way too hard for my fish and plants. So, when I did my water changes, the first water change I did 5 gallons of RO water. The KH went down to 5 and the GH down to 196 ppm. Since then I have completed 2 more water changes each with 2.5 gallons of RO water and 2.5 gallons of tap water mixed. The KH has come down to 3 degrees, which seems good for my fish and live plants. But the GH has remained high, at 196 ppm.

Through all of this, the pH has remained stable at 7.6.

Is this a good level to stay at? Is there a way to bring down the GH a little more or should I not worry about it? (According to the API kit instructions, a GH of 11 degrees (196 ppm) is good for marine fish, not tropical fish.)

Can I bring down the GH without bringing down the KH even more? I think it wouldn't be good to bring the KH down any more. . .

 

coralbandit and AquaticJ both do this. They will be around.

 

My Oklahoma water is very similar to yours; very hard with a PH around 8.2. I've successfully kept Tiger Barbs, Cory cats, even Discus in it w/o altering the chemical makeup. Unless you plan to breed a fish with specific requirements regarding water chemistry, it's best not to alter the water. In most cases a rebound effect occurs when water is chemically altered. Not a good thing for the fish.

 

My Oklahoma water is very similar to yours; very hard with a PH around 8.2. I've successfully kept Tiger Barbs, Cory cats, even Discus in it w/o altering the chemical makeup. Unless you plan to breed a fish with specific requirements regarding water chemistry, it's best not to alter the water. In most cases a rebound effect occurs when water is chemically altered. Not a good thing for the fish.

Okay, yes, you're right, I don't want to chemically alter the water. Just thinking of simple things like doing water changes with RO water and I also read that Baking Soda can bring up the KH. (So, if the RO water brings the KH down too far, maybe I can add baking soda?) It seems so far the RO water has brought only the KH down significantly and not the GH. I'm a little confused about why the RO water brought the KH down so much, but not the GH down. . .

Basically, if I found the right balance, I was hoping to just do my water changes every week with a portion of RO water and keep all my levels consistent. Maybe I can just stick with half RO water and half tap water? Since that seems to have brought the KH to a good level and maybe the GH is fine?

I've done a lot of reading about KH and GH, but either I haven't found the right information on it or I didn't understand it and so haven't made total sense of it yet!! Lol. Can anyone explain why the RO water has brought the KH down but not the GH?

Thanks!

 

it's best not to alter the water. In most cases a rebound effect occurs when water is chemically altered. Not a good thing for the fish.

What do you think of using part RO water/part tap water? Do you consider that chemically altering the water and a bad idea?

 

A lot of keepers mix tap water w/RO water, but usually have a specific goal in mind. If your goal is just to sustain the listed stock (Tiger Barbs & Cories) I would just treat the tap water with a quality water conditioner and let it go as that.

 

A lot of keepers mix tap water w/RO water, but usually have a specific goal in mind. If your goal is just to sustain the listed stock (Tiger Barbs & Cories) I would just treat the tap water with a quality water conditioner and let it go as that.

My goal was just to bring the hardness of the water down a bit because I thought it wasn't good for the fish! But, it sounds like you're saying that the fish will do just fine in hard water? And unless I'm trying to breed them, then there's no reason to change the water, right?

 

I’d say your fish aren’t sensitive enough/your water isn’t hard for it to be that important. My tap PH is 8.2 and my GH is 180ppm and I have some gorgeous fat Cories. Now if you’re wanting to breed the Cories and have access to RO, yeah sure, but if you’re just keeping them they should be fine. I use RO to breed Rams, but that's it. If you want to move GH and KH separately you need to start with pure RO water and buffer them with something different. For example say you want a KH of 100, but only a GH of 50. Start with pure RO, use Seachem alkaline buffer to adjust KH to there, then Seachem Equilibrium to adjust GH.

I was actually having a conversation with coralbandit about this, we both breed Rams and I’ve been going off of GH for them, while he’s been going of TDS. He sent me a TDS meter and we found out that my tap is only 170 TDS, while his is 250 or maybe 350, but his PH is lower than mine, as is his GH.