Carbonate Hardness

[Juannie]

Can anyone explain to me in "easy" terms how you measure this properly.
Thanks:ezpi_wink1:

[Fishguy2727]

With a carbonate hardness test kit.

[Juannie]

I purchased one and did exactly what is says but I still don't understand what the reading means, it was 30ppm. Is this a good thing for tropicals or bad? It doesn't explain what is good or bad on the kit.

[Lady Hobbs]

There should have been a chart of some kind that tells you. I got a kit not long ago and looked everywhere for a chart. It was on the inside of the label. Like....why would anyone think to look there!

This stuff is Greek to me. All I know is that KH is how much alkaline is in the water and not how hard the water is at all.

[dev]

1 dKH (german degree of hardness) equals 17.86 parts per million, so your KH is just about 2 dKH.

KH on it's own doesnt matter much to your tropical fish. The carbonates does however provide a buffer against acids, and will greatly influence the pH value of your tank.

[RobbieG]

I purchased one and did exactly what is says but I still don't understand what the reading means, it was 30ppm. Is this a good thing for tropicals or bad? It doesn't explain what is good or bad on the kit.

Why are you testing it?

[Fishguy2727]

Good or not depends on exactly what fish you have.
What fish do you have?

[dev]

Good or not depends on exactly what fish you have.

Perhaps you have it confused with total hardness? The KH is important, but only because it affects the pH. As I'm sure you know, you won't find any KH levels listed in a fish atlas.

If the pH is where you want it, you don't have to worry about carbonates - though it is good to have at least some carbonate hardness to provide a stability in the pH.

These general reccomendations are often given, but again they relate to the pH requirement of the fish. Having a KH within these ranges will give a pH in the required range for most water. All are in german degrees.

South-American: 0-2
Asian: 1-4
Community: 4-8
Malawi: 10-12
Tanganyika:10-14

These are only guidelines on how to reach the desired pH level. You should really measure the pH and add or remove carbonates as required to meet the pH requirement of the fish. If you then measure the KH you will usually find it to be in the ranges above. Adding CO2 does of course change all of this.

[Fishguy2727]

That is exactly what I meant. The carbonate hardness tends to control the pH, which is why it is important to the fish. My water is very hard so it will hold very high, so I have to use buffers to keep it down for my discus. I think it is more accurate to say that carbonate hardness will hold a pH up, rather than stable. So a low carbonate hardness will allow the pH to stay low. This is also why tanks already low in pH (and therefore low in carbonate harndess) tend to be more likely to drop in pH, and faster.

[Juannie]

In my previous tank the pH kept dropping pretty much every couple of days. The fish are now in a new larger tank and it's stable around 7 - although I've had trouble with the pH going up and down - usually because of my tap water so I've been using a buffer to drop it to 7. In my tank I have:

Kribs, 1 firemouth, 1 convict, various med size tetras, 2 severums, 1 gold gourami, corys, algae eaters.

I thought testing the carbonate hardness would help, I know that the colour changed very quickly when i did the test, I think it was around 30ppm.

[Chrona]

In my previous tank the pH kept dropping pretty much every couple of days. The fish are now in a new larger tank and it's stable around 7 - although I've had trouble with the pH going up and down - usually because of my tap water so I've been using a buffer to drop it to 7. In my tank I have:

Kribs, 1 firemouth, 1 convict, various med size tetras, 2 severums, 1 gold gourami, corys, algae eaters.

I thought testing the carbonate hardness would help, I know that the colour changed very quickly when i did the test, I think it was around 30ppm.

What else do you have in the tank that could affect the pH? (ie driftwood, etc). In general, you kH has to be completely neutralized by plant intake (takes a LOT of plants), or acids (also takes quite some time with 2.0 to start with) before the pH starts fluctuating. Stop using the buffer and figure out the root cause of the pH swings.

[Juannie]

What else do you have in the tank that could affect the pH? (ie driftwood, etc). In general, you kH has to be completely neutralized by plant intake (takes a LOT of plants), or acids (also takes quite some time with 2.0 to start with) before the pH starts fluctuating. Stop using the buffer and figure out the root cause of the pH swings.

I've had the same piece of driftwood in the tank for the past 3 or so years. The pH started dropping all of a sudden one day, nothing had changed. I did add plants and started having more trouble, they eventually were removed but still it didn't settle. I put shells in too increase the pH and keep it a bit more steady. That was ongoing for about 6 months.

When I put them into the larger tank nothing was new except the water from our tap had a higher pH. Obviously this affected the tank water and the pH spiked so I put another piece of driftwood in from the other tank and took out all the shells to see if it would settle down. It's now sitting around 7, but everytime I do a water change I have to use the pH 7 buffer so it's not spiked dramatically. I am totally stumped as too why the pH was dropping quickly in the other tank, now it's around 7, I just want to make sure my fish are ok because now I've lost one krib this week with another 2 or 3 that haven't been looking too good, it's really weird.

[Chrona]

What do you currently have in the tank? (I mean everything except for the fish)

[Juannie]

2 pieces of driftwood (been in there forever), 1 ship, plastic plants, fake rock ornaments, rocks (purchased from pet store about 3 years ago), there's actually nothing new except some of the plastic plants.

[Chrona]

2 pieces of driftwood (been in there forever), 1 ship, plastic plants, fake rock ornaments, rocks (purchased from pet store about 3 years ago), there's actually nothing new except some of the plastic plants.

I would take the driftwood and (real) rocks out. Give it a week and a water change and see what happens.

[Juannie]

I would take the driftwood and (real) rocks out. Give it a week and a water change and see what happens.

Ok thank you, how do they affect the pH/carbonate hardness levels?

[Chrona]

Ok thank you, how do they affect the pH/carbonate hardness levels?

Driftwood softens the water and lowers the pH. The rocks may contain carbonates that are raising your kH/pH at the same time, resulting in the screwy water chemistry you are describing. Also, no crushed corals for the substrate, at least, not for the fish you have.

[Juannie]

Very interesting, thanks I'll give it a go. I actually added the extra piece of driftwood to lower the pH as it was way too high. I have sand in the bottom so there's no added coral in there. Hopefully this will help as I've made no new additions to the tank besides the extra plastic plants & piece of driftwood.

Thanks for your advice I appreciate it.

[Chrona]

Also, no more pH additives either. I suspect that whatever you are using is temporarily bringing down the pH, but is eventually overcome by the innate hardness/alkalinity of the water.

Also, keep a track of how the pH changes every 12 hours or so.

[Juannie]

Thank you, you've been a big help.:19: