Need help-Is this calcium ?

ryker · Dec 28, 2015

Does this look like calcium. The pool is now about 1 1/2 years old. I have a TF 100 test kit for a long time now, have have kept chem numbers inline for a TFP. If this is calcium, I am clueless as what is causing it, since I do my nown test, and keep the water inline with the numbers that they should be. The other things that has me confused if it is, why there is not more of it around the pool.

The picture is of grout inbetween tile at the water line. There are (I guess) over 150 of these joints around the pool. and there are only 6 to 8 joints like this. If it was because of calcium, seems like there should be more. Nothing I do, (we have well water, with no iron), in balancing the water, changes this or seems to stop it from happening. It also seems to crystallize in the same spots. Never seems to start anything, anywhere else in the pool. I can take pics of a couple of the other spots if you need. Also, here are my last test, from yesterday. Any help will be greatly appreciated.

C 5.5
PH 7.8
CH 300
TA 80
CYA 35

tim5055 · Dec 28, 2015

No, I don't think it is calcium scale. It looks more like "Grout Efflorescence" which I get on my pool.

You can check out my thread from before which has photos, some discussion and how I handle mine - Grout Efflorescence in Several Areas

Divin Dave · Dec 28, 2015

I agree with Tim, its most likely efflorescence.

duraleigh · Dec 29, 2015

Can't see from the pic but efflorescence occurs when water is migrating to the front of the tile because of water behind (and above) the tile.

Yours appears to be normal water line tile with the slope going away from the face of the tile. That's a pretty unusual spot for efflorescence to occur although it looks like it.

Got any more pics that show how the tile relates to the ground behind it?

ryker · Dec 29, 2015

pic 1 is of the original pic at distant to show how the tile is under the lip of deck, extends past chair legs 12 feet, you can also see a drain running across (back about 2 1/2 ft)

pic 2 is around corner from there in the end of pool

pic 3 is on the curved part (it's an outside corner) of the pool where it rounds into the swim out

These have been there awhile now, I think they are probably permanent now.

I can take more pics if needed. like to know. again, in all the joints in the pool, there are only about 5 or 6 like this. seems if it was calcium, should be more.

thanks greatly for your help

JoyfulNoise · Dec 29, 2015

Does it come off easily if you spray a little diluted muriatic acid on it?

It looks like it might be some source of calcium from behind the grout coming through the porous grout surface. The source could possibly be the cement of the gunite shell itself. Unreacted calcium hydroxide leaches through the grout joint and then converts to calcium carbonate on the surface of the grout in contact with the water. It likely will subside over time but in the meantime you can try cleaning off the grout joint with a fine pumice stone or a stiff nylon brush. Perhaps some elbow grease and little dilute MA will do the trick. After it's clean, see how long it takes for it to show up again. One other thing you could do, but it would be a royal pain and a lot of fine detail work, is to drain the pool below the tile line, clean off the calcium deposits on the grout surfaces and then seal them with a grout sealer suitable for wet environments (kind of like what is used in tiled showers). The sealant will make the grout more impervious to water and mineral infiltrations.

duraleigh · Dec 29, 2015

Yeah, I think everyone else has it right with efflorescence......thanks for those pics and thanks for telling us it's only 5 or 6 tiles.

Now, the bad news is there is there is no short term fix. Keep it wiped clean with muriatic acid and it will eventually go away on it's own.

I like JN's sealing idea above but I am too old and cranky to tackle that job .