Not sure it's a stain.. but it won't brush

[waste]

I'm just gonna put some thoughts here to see if someone else can't complete them.

I've been trying to figure this one out since it started last week.
1) We've got 'deposits/ stains' that tend to be where the water is shallower and near returns.
2) Ascorbic acid (the lemon) doesn't seem to have an effect.
3) Brushing seems to work, if caught eary enough (and the pool cleaner keeps it away, in the areas it can get to)
4) The substance in ? is brownish and gritty (my initial thought on this is calcium- but w/o it being universal to the pool, that doesn't seem right)
5) Would recommend solid chlorine, pucks or a satchel of dyr chlorine, to see if it helps, directly on a portion of the stain (Mike, you 'tested' for metals w/ the lemon, next test is for organics w/ concentrated cl on a spot)


Is there something that the return water might do to increase the precipitation of calcium?? (I can't think of anything that the freshly 'energised in the cell' water would have that could cause this)

When caught early enough, either by brushing or the passing of the cleaner, it doesn't take hold.

Thin coat of plaster, which is bleeding through??

Some sort of bypass through the filter (i'm thinking it's not sand, cause sand will just brush away, perhaps some finer organic which will pass through the sand and concentrate in the return areas - again, try the puck or cal-hypo) - or even an 'infection' of the filter itself.

That's about it form me on this.
(BTW-Big_D gave a great! response to the light ? earlier today (saved me a post by mentioning the plastic wheel in the SAM lights, and had nice input as to the lumens ))

AS I said, I don't know what it is, but perhaps something I've posted will 'trigger' a response from someone else.
Mike, I hope this turnes out as well as the 'CPB' question!!!

[mphare]

Thanks everyone.

Now that I've got some salt in the pool, and the SWG is making chlorine.. I'm seeing less of the buildup.

The concentrated CL on the affected area seems like the next step.

While it doesn't feel organic (I expect organic to feel slippery, not gritty, but I may be wrong about that) the fact that now that I have CL the stain is less, seems to point in that direction.

[Big_D]

Based on your information you probably have some type of algae which is probably not in the substrate yet at least. Good for you and I bet you are right it is more of a chemical maintenance issue. I also agree you can add some regular old bleach and clear up most of those. My old pool would get blooms in the summer since the circulation was poor. Back then I did not know better and I would buy that expensive shock to kill it.

On the new pool I also have a SWG but I will dump in a gallon on occasion to make sure those bad organisms are in check. Also living here in Texas that summer heat is rough on Chlorine and pool use is high so it is too cheap not to stay ahead of the game.