The paint from our pool clouds off when brushed only a month after being painted. Chemical test done every week by pool shop and are guided by them as to what to add to pool. The only thing I can add is that after a spell of rain the pool turned green and was advised to shock dose, which we did and cleared the water.
A month later when people used the pool it would cloud the water and go green, starting the cycle all over again. A costly exercise having to use flocking agents and water polishers. We feel this is not calcium build up. Drained & rubbed with metho and no change.
Another problem is the we only have a limited catch tank for backwashing pool Dimensions - 4 mtr x 10mtr Capacity - 75000 lt Sand filter and salt chlorination
Thanks for your question Colin
First, you don't already have one, I would advise you to get a Taylor Reagent FAS-DPD K-2006 pool water test kit. It's the best on the market and will give you the most accurate pool chemical readings.
There are a couple of kinds of pool paint that you can use. Epoxy paint is generally used for new pools or pools already painted with Epoxy. This kind of paint normally lasts about 7 - 10 years.
Next is chlorinated rubber base pool paint. It's not as durable or long-lasting, but it's a good middle of the road paint and should last about 3 - 5 years.
Last is water based acrylic pool paint. This is easy to apply on most surfaces, normally for commercial uses, and lasts about 2 - 3 years.
Most premature pool paint fading and chalking are normally due to improper pool water chemistry. This can result in dull or hazy water,
or a white powder residue coming from the pool surface that was painted.
Keep these readings:
Chlorine - 1.5ppm - 3.5ppm pH - 7.6 - 7.8 Total alkalinity - 80 - 100ppm. For salt pool you can go to 60 - 80ppm for the alkalinity. Hardness - 150ppm - 250ppm. Try not to go over 250ppm while you have a salt cell chlorine generator. Any more than this and you run the risk of clogging up the cell with calcium.
Now for your algae problems. If you add pool chlorine and go back 24 hours later and there's none after doing a chlorine test, the problem could be a lack of cyanuric acid (CYA). This is the stabilizer for the chlorine. You need to get the CYA up between 30 - 50ppm.
These links will tell you how to get the CYA up to an acceptable range and how shock your pool:
Be sure your sand filter is running properly. You can open the top and feel the sand. If it's sticky you may need to degrease the filter. Check for channeling as well. Feel around the inside sides of the filter. If there are pits or holes, that's channeling, so a good degrease is in order. The one I've always used is called "Filter Fresh" which should be available at any pool supply store.
Backwash when the pressure gets about 8 - 10psi over your "just backwashed" pressure. Keep the skimmers, pump basket, and bottom drain free from debris. With proper water balancing and good filtration, they're shouldn't be much need to clarifiers or water polishers. Hope this helps good luck with your pool.