kH

[wetwetwet]

I've got a tank with a very low kH reading - 2ish, which I believe can be a problem with keeping a stable pH and is quite common in tanks that have been established for a while. Well its not my tank but in one of my pubs and so doesn't get the best of care but I'm trying to change things in that respect.

What problems can this cause?

and what should I add to the tank to raise the kH - I know you can buy buffers, so could someone recomend one or something natural that can be added?

...and what kH should I be aiming for - its a community set-up.

 

[Great Lakes]

WWW, KH or GH? KH readings are generally lower than GH.

 

[wetwetwet]

yep KH GL

the GH seems fine at 14

 

[reg2k2]

Trying to deal w/ low KH myself.
Think 3-4.5deg is a min. to shoot for.???

I added cr.coral to mine (water was soft overall), which seemed to help a bit (raising KH to 3deg). Mostly seems to raise the GH; it's been rising steadily, but the KH still crashes if I let the tank go too long.

Just read adding turbulence to water surface can help by driving off CO2. Recently turned down my air, so I'm gonna shoot it back up, see if that don't help.

Adding baking soda raises KH, but I haven't tried that yet.

Is your tap that soft?

 

[William]

Ok this is an article by our own stickle!

Carbonate Hardness

Carbonate Hardness, also referred to as kH, is the result of contact between water (H2O) containing carbon dioxide (CO2) and lime or chalk (CaCO3). Carbon dioxide reduces calcium carbonate to calcium hydrogen carbonate, which imparts carbonate hardness to nearly all fresh waters.

If the pH is acidic then the water will have a low kH value. When a high kH is maintained, the pH will stay stable and will then rarely fall. As the pH of the water becomes more acid, the kH decreases making the pH unstable, also stunting the growth of plants. kH can be easily increased using kH up and Carbonate Hardness Test Kit

When breeding fish, carbonate hardness influences egg maturation, embryo hatching, and the wellbeing of the fry. As each species of fish are different and prefer different KH values, it is worth doing some research into each specific fish before trying to breed them.


Of course i can take no credit for it he'd shoot me down if I tried. IT has lots of useful info in it though

 

[wetwetwet]

reg, I don't think tap water is that soft in this area, just that the maintenance on this tank hasn't been good and its been established for a couple of years

Will sea shells achive the same as coral? I dont like the idea of adding baking soda unless you can suggest a dosage? Or would aquarium salt have an effect?

William, .....IT and usefull info - whats IT?

 

[reg2k2]

I was just wonderin' if maybe a few wc's might not straighten it out.??

Yeah, shells should do the same. Someone had suggested tufa. I didn't find it here (unless it's called something else). Someone at LFS also suggested fiji rock.

You might run a search on low ph, think there were some other suggestions, and prob. the dosage for the b.soda.

I'm not sure on the salt, but it might work. I'm still trying to understand all of this myself. Not sure if William/Stick's post contradicts the thing about CO2, but I read injecting it was a way to lower KH. (?)

 

[William]

Carbon dioxide reduces calcium carbonate to calcium hydrogen carbonate,

From my chemistry skills I think he means that as you add CO2 you will get less KH like you say because the water becomes more acidic due to CO2 and the calcium carbonate gets reduced (addition of hydrogen = reduction)

Seashells should achieve the same but make sure they are very well cleaned, there is a lot of junk on the beaches these days and I would hate to see your fish being poisoned. I also read somewhere that they leach unwanted materials into the water what these materials are I don't know.

Better safe than sorry

 

[reg2k2]

Thx, William.

Let's see if I understand this: it's the calcium carbonate (w/out the hydrogen) that imparts carb. hardness to water.?

In which case, that sentence is not written clearly.
And I'm not a complete dimwit?

 

[William]

Ok you've got me all confused now Reg! I'm doing my alevel chemistry so I should be able to figure this one out, the wording is a bit confusing though!!

Basically when the substance in the water is CaCO3 calcium carbonate you get higher KH of the water, the imparting I'm not quite sure what he means to be honest.


But when waters acidic the Calcium Carbonate acts as a buffer, it takes the H+ ions from the solution (H+ ions = acid) by becoming Calcium hydrogen carbonate it removes the acid, however calcium hydrogen carbonate no longer adds 'hardness' to the water so it doesn't affect the KH scale, it is pretty stable I think and so can't be used by organisms in the tank until the pH rises and the H+ ions move back into solution.

 

[reg2k2]

Oh, now that didn't help!!!

I'll have to read it again later.

 

[wetwetwet]

Ermmmm.....


....all I wanted to do was to raise the KH a little

 

[shtinkypuppie]

if you can find crushed oyster shells at a local farm feed store, those would be great. Natural calcium carbonate. Also crushed coral and sea shells. Be careful about changing things too fast.

 

[Great Lakes]

OK, you should be shooting for a kh of aoround 4. The best home made buffer is Arm and Hammer baking, and Washing soda. You mix six parts baking soda to one part washing soda and dose at one heaping teaspoon per 25 gallons. I would do this every two to three days till you are at the level you wish. Baking soda alone will raise your hardnees, but drop ph levels slightly. Washing soda will also raise hardness, but can raise ph dramatically, therefore the combination of the two BUFFER each other to negate the effects on ph while raising your hardness. You might also want to consider the gas exchange going on in the tank. One of the great contributors to soft water is excess CO2.