Culator -- Solution or Just Another "Pool Store" Product?

[waterbear]

The higher calcium is for fiberglass pools. There is some empirical evidence that it helps lessen iron staining and cobalt spotting which fiberglass pools are prone to more so than other pool surfaces.

[PoolDoc]

I very much doubt that the calcium is directly preventing staining.

I suspect that what is happening is that you are creating fine calcium precipitates in the filter, which because of flow and surface area tend to get 'stained' BEFORE the pool does.

If my analysis is correct, this is directly related to the method I've mentioned of using cal hypo to remove metals from the water.

[JimK]

The higher calcium is for fiberglass pools. There is some empirical evidence that it helps lessen iron staining and cobalt spotting which fiberglass pools are prone to more so than other pool surfaces.

I very much doubt that the calcium is directly preventing staining.

I suspect that what is happening is that you are creating fine calcium precipitates in the filter, which because of flow and surface area tend to get 'stained' BEFORE the pool does.

If my analysis is correct, this is directly related to the method I've mentioned of using cal hypo to remove metals from the water.

Thanks.

[waterbear]

I very much doubt that the calcium is directly preventing staining.

I suspect that what is happening is that you are creating fine calcium precipitates in the filter, which because of flow and surface area tend to get 'stained' BEFORE the pool does.

If my analysis is correct, this is directly related to the method I've mentioned of using cal hypo to remove metals from the water.

IF that is the case then perhaps this is an easier way to achieve this. I know of others with fiberglass pools who have done this and had similar results. One thing that I did notice is that one time when I let the calcium hardness drop (I fill with softened water) I got stains again. My fill water has no iron (my city water is reverse osmosis where I live and very soft. They add calcium to bring the hardness up some and my house also has a water softener. I suspect the iron was introduces by "pool salt" since the first stains I every saw were in the spot the salt sat to dissolve.)

[PoolDoc]

Waterbear,

I don't see how having DISSOLVED calcium would help; maybe there's some sort of ionic effect that raises the staining threshold. If so maybe Chem_Geek has some info on that. But what I've pretty much confirmed is that if you make the water PASS THROUGH calcium particles, especially in a high oxidizing state (ie, cal hypo via the skimmer) you WILL stain the heck out of the goo on the filter.

Now, if you are precipitating calcium onto the filter, maybe THAT will help.

[chem geek]

I don't see where doubly positive calcium ions are going to help precipitate doubly charged positive copper or triply charged positive iron since these will repel each other. I think Ben's explanation is more likely since adding Cal-Hypo into pool water that is already close to saturated with calcium carbonate will cause both the CH and pH to go up substantially causing calcium carbonate to precipitate. The higher pH will cause the metal ions to form metal oxides-hydroxides so they'd all precipitate together into the filter.

In theory, just raising the pH should precipitate the metal, but perhaps it's normally super-saturated and needs something to help its precipitation, such as calcium carbonate. This is all just an educated guess, however.