Using Limestone to offset CO2 injection

[beviking]

Is this plausible? Seeing enough threads concerning Ca deficiency has me wondering if one had limestone in the tank injected with CO2...but would it leach other things not fish/plant friendly? :read:

[Blinky]

I'm not sure about limestone, but I use a bag of Aragonite sand in my canister. Plants seem happy, but I haven't tested Ca levels in a while so I'm not sure how much it's actually adding :)

[Egon von Hacklh]

Caution: I am new to aquarium keeping, but I have experience in hydroponics.

Dolomite lime, available at most hardware or garden stores, is the type of lime you would need to use. It is an excellent source of calcium and magnesium. Other types of lime will wreck your pH quickly.

Place a small amount, say 1/4 cup, in a length of pantyhose and tie it off and hang that in your tank for a few days to try it out prior to making it a permanent addition to your substrate. Dolomite lime is usually very fine and turns into a "sludge" under water, so you may want to hide the pantyhose package at the back of the tank rather than incorporating it into your substrate.

Dolomite lime, in my experience, will not raise pH above mid 7's, and is a far better solution than sodium bicarbonate, as plants generally don't care for the additional sodium.

Please be aware that this will also increase hardness, as free Ca++ and Mg++ ions are released.

Stay away from hydrated or other types of lime, unless you really want a drastic increase in pH.

Hope this helps.

[RTR]

I'm confused. What does CO2 supplement have to do with Ca++ deficiency as opposed to any other trace element or macronutrient dficiency? If you need trace elements, add them, preferably with a supplement with the correct Ca:Mg ratio.

[beviking]

I'm confused....

So what's new!?! :laugh: :laugh: :laugh: ;)

I ask because limestone is plentiful (the rock, not lime Egon but helpful reply anyway, thank you! Nice slabs, perfect for designing rock ledges, walls, etc...). If it would alleviate one less dosing of "X" than why not?
Some that dose micro/macro nutrients also dose Mg and/or Ca seperately. So I thought could we "kill two birds with one stone"? Design with materials that would benefit the plants and reduce/eliminate dosing one (or more) more thing.
I wasn't directly correlating CO2 to Ca deficiency alone (now that would be silly!), only questioning if using limestone could help alleviate Ca deficiency.
Hope this alleviates your confusion. :)

[daveedka]

Bill,
Dolemite and limestone are similar in what they will do for your tank. the dolimite has a more consistant MG to CA ratio than typical run of the mill limestone.

Either way IME they both top out at about 7.6 ph, and quit dissolving rapidly if at all at that point. So neither will raise your ph above that without some sort of additionaly measure to alter it.

sodium bicarbonate as mentioned will take it higher, but limestone is not sodium bicarb. And of course sodium bicarb will not give you any calcium.

Now for the crux of the matter. with good co2 injection and a ph kept below 7.6 you will essentially have a slow calcium reactor going in your tank. Your problem will be that Kh will continue to climb slowly at all times. My change water goes in at 2-3 kh and my tanks stay 6+ with limestone and crushed coral both in the mix. I change nearly 50% a week so there is definately a constant KH increase in the tank. But even with the constant levels of dissolving rock, I have to dose additional calcium to keep the plants happy. When starting with very soft water it is difficult to dissolve enough to get the needed calcium IME. In other words lime and or crushed coral will help (either one about the same, but won't stop your need to dose calcium if your water is anywhere near as soft as mine.

On the flip side, if you want to aquascape with flagstone, you certainly won't hurt your situation by doing so. and the tank should look pretty cool that way.
Dave

[beviking]

Thanks Dave! My KH is around 8-9 (varies during the year from the tap) and if I skip water changes (to every other week) it begins to drop in the tank.
Flagstone is plentiful so I may give it a shot.

[telecubby]

I imagine there must be a use for small amounts when used with alot of driftwood in say larger tanks as it works so well in nature. you could even get it in diferant composite blends that would time dose it the more you need the softer or more limestone you could use, if you dont need much then you get it mixxed with say quartz or granite so the veins leach out slowly but most say don't use anything chaulky (limestone!)