Limestone as a buffer for R.O. water in plant tank?

[DSenn]

I was wondering--amongst the myriad of questions I am bringing to this forum --if Limestone can be used in a plant tank and, more specifically, if it can be used as a buffer for straight R.O. water. I know it is probably not 'recommended' to use Limestone, but I already have it available to me and it looks great, and was wondering if this is feasible.

 

[rich311k]

Why I thought you were lowering the PH?

 

[roka64]

Moving to FW Discussion section.

 

[DSenn]

The Limestone is for anther tank. I was thinking of using straight R.O. water (or mixing it with a little tap) and using the Limestone to buffer the R.O. water for a soft water tank. With the R.O. having no buffering and the Limestone having at least some, I thought they might make a good mix, but I'm not sure. Any thoughts?

 

[Purrbox]

Fill a bucket with water, throw in a piece of limestone and let sit. Test the GH/KH/pH periodically to see the effects.

 

[DSenn]

I've actually done that Purrbox, and I did notice that it gave some hardness and pH. I just know that Limestone is not typically used for a softwater plant tank, and I didn't know if there was anything 'unsafe' about using this rock besides the obvious GH/KH/pH issues. With the R.O. water, the Limestone may just give me the buffering I need

 

[Purrbox]

Basically as long as the rock doesn't have any mineral deposits (copper, etc) that would cause problems, and you are getting the desired effects on GH/KH/pH there shouldn't be any problems with using it.

 

[DSenn]

Purrbox,

I was wondering if you think that the Limestone will 'level off' in how much it adds Gh and KH to my R.O. water over time. I do think the Limestone will give me the buffering I need, but I am wondering if it will exceed the low numbers I am looking for and make my water too hard. I am assuming and hoping that the amount (or rate) of Limestone dissolved into the water will even out and remain consistent once it reaches a certain point, and I can help control higher levels of hardness with R.O. water changes, but I was curious as to what you thought.

Also...even if I do reach a suitable number for dKH/GH with the Limestone, do you think I should add anything 'extra' (like maybe some tap water), or do you think that the 'type' of hardness the Limestone adds will be sufficient?

Thanks for the insight!

Dan

 

[sumpnfishy]

I had always heard that putting limestone in the tank could cause real problems because it will continue to add to the water.

I had been using straigt RO water in my tank and when I finally learned about buffering I found just mixing my tap (well) water with the RO I could get my KH to a reasonable level. Of course that depends on your tap water's KH (mine is 18).

I would at least follow Purrbox's idea of putting in a bucket of your water and monitor it for a month or so to see if it keeps raising the pH / KH.

me 2 cents

 

[rich311k]

I imagine it will reach a limit of how much hardness it will add to the water and would remain steady after that point is reached. What the numbers will be I have no idea.

 

[Purrbox]

I imagine it will reach a limit of how much hardness it will add to the water and would remain steady after that point is reached. What the numbers will be I have no idea.

Exactly. That's why I recommended placing the rock in the bucket and testing. It's the best way to get a fairly solid answer on what the effects are going to be. I'd say that once you get the same results for two weeks straight (3 consective tests one week apart), you could probably proceed with a relative degree of certainty.

I don't know what the chemical composition of Lime Stone is, so I have no way of knowing what would need to be added. Perhaps test for GH and if unaffected by the Limestone add some RO Right?

 

[sumpnfishy]

I found this on a site about limestone rocks in aquariums. This was what I was thinking of: "Minerals don’t stay suspended in water for very long, and so the limestone helps to keep your pH stable by continuously leaching calcium carbonate into the water."

So it does seem like once you've determined what your rock delivers in your tank (size/ filtration/ PWC might make a difference), you should be OK. The site was talking about using them in African Cichlid tanks.

I was told not to use Limestone on a waterfall for my pond. Different situation there.

 

[Purrbox]

If it's only leaching Calcium Carbonate, then you're going to be missing Magnesium (the other part of GH) and trace minerals. You could either dose these in the necessary proportions or mix in a little of your tap water. I'd use which ever is easiest for getting your desired results.

 

[DSenn]

I agree that is will probably reach an equilibrium point and remain steady. I don't know what those numbers will be either, but I can't imagine it will be that high considering I am using R.O. water. I have my rocks in my tank now with 100% R.O. water, and that's all. I will report back on the numbers as they go up, in case anyone is interested.

Here is an article I was reading that goes along with what I am trying to do:

Re: Reconstituting aquarium water

 

[DSenn]

Yeah, good point Purrbox. To be on the safe side, I was either going to mix a gallon of tap (4 gallon R.O.:1 gallon tap) or R.O. Right with each water change. For the time being, I have to wait a couple weeks and see how much these Limestone dissolves into my R.O. Really, this is a pretty cool experiment, especially for those looking for ways to buffer soft water. Thanks for the help. I'll post when I get some numbers.

 

[DSenn]

these = this

 

[jsoong]

I agree that is will probably reach an equilibrium point and remain steady. I don't know what those numbers will be either, but I can't imagine it will be that high considering I am using R.O. water. I have my rocks in my tank now with 100% R.O. water, and that's all. I will report back on the numbers as they go up, in case anyone is interested.

Here is an article I was reading that goes along with what I am trying to do:

Re: Reconstituting aquarium water

Actually the equilibrium point of CaCO3 (limestone) is 7.8 to 8.0 ...(as reported in the KRIB FAQ)... you might have to wait quite a while (weeks) for the water to equilibrate as a big chunk of limestone has less surface area compared to say a handful of crushed coral.

 

[DSenn]

Does this equilibrium point change if I am using R.O. water with no minerals? Wouldn't the amount of Limestone you have in the tank affect the equilibrium point?

 

[DSenn]

Would the Limestone ever reach it's equilibrium point if I am doing a weekly water change of mostly R.O. water?

 

[SpeedEuphoria]

these = this

hey you know there is an "edit" button on the post, next to the "quote" button. This is so you can edit a post you just made instead of making another post.