Pool - Heavy cal deposit

[telboy]

I there anything that can be added to pool water whilst its covered during the winter months to gradually dissolve cal deposits on the pool sides

This particular pool has a heavy build-up of cal above and below the waterline, Agua Fuerte is a solution but its too corrosive on the grout, the pool suffered during this very hot Summer with rapid evaporation and continuous topping up. The mosaic pool tiles are prone to dropping off if too much elbow grease is used, the pool was built using tiles that weren't mesh-backed but gummed paper-fronted.

terry

[TorreDelAguila]

Paper-fronted tiles are no problem, just a little more messy for builders to install in the first place - mesh-backed is easier these days. If tiles are dropping off, it's down to the adhesive used or quality of work, or subsequent over-use of acid.

We've had periods of cal formation, too. You are right to avoid adding acid, to preserve the grout. Missing grout in turn allows any acid to get behind the tiles - vicious circle!

Would simply suggest that you use normal 5-in-1 multifunction tablets over the coming winter, but 'overdose' with these for a while - say 3-4 weeks - and let the pump do a reasonable amount of circulation. This will show up as the chlorine level being about 3ppm, or even 5ppm. Good tablets will not increase acidity of the pool, but will act as softeners for the water, and should allow the cal to dissolve back into the water.

I have a favourite brand of 5-in-1 Complex Tabletas, made by Sogeclor. We get these from our local branch of Proinco (plumbers merchants). We've had other brands, cheaper and more expensive, which don't work anything like as well. Realise this is a personal choice; everyone will have something that works well for them!

PS
Bomb-proof (acid resistant) grouting does exist, if you every need to re-grout the pool. It's called "Epostuk" epoxy grout, and is made by Technokolla (in Italy). It's a two-pack grout, which actually adheres tenaciously to the vitreous tile edges, rather than just sitting between them, which normal grout does. Available from good tile stockists, and is food industry and municipal pool/hospital grade.
If you ever opt for this, I have some tips for using it.

[probe]

The only way that you will get the cal to disappear is to reduce the pH. As you have the whole of the winter it should be possible to do this very gradually. Test the pH and then lower it step by step until the cal goes. You can use pH menos but I am led to believe that this is just an expensive for of agua fuerte. This gentle approach should preserve your grout.

[TorreDelAguila]

What water pH figure would you recommend aiming at?

[probe]

7.4 is neutral so shouldn't gain cal at or below this level

[Beachcomber]

The pH scale is graduated from 0,0 to 14,0 so 7,0 is neutral not 7,4 which is the level at which the pool should be maintained, slightly on the alkali side of neutral.

You can safely aim for 7,0 or a little lower. This combined with regular sweeping with a proper pool brush will remove the build up of cal albeit very gradually.

I use sodium bisulphate as a pH reducer and I would never use agua fuerte in my pool but this is just my preference. Sid would probably call it an obsession!

[probe]

Of course 7.0 is neutral - mental aberration - apologies

[Martin Page]

If your water supply is alkali - I personal find trying to hold a pH at 6.8 (acid) soon swings back to 7.4 very quickly