A couple of quick responses.

1. So far as I know, potassium monopersulfate is NOT a microbiocide -- and it's not a great oxidizer. If you don't have an effective microbiocide in that pool, it's not a safe pool!

2. There two products sold in the USA as "mustard algae" products -- ammonium sulfate or chloride OR sodium bromide. Both are used in conjunction with chlorine; neither has any effect on mustard algae alone; both CHEMICALS are available in Europe, just not via pool distribution.

3. If you want us to help you, you'll need to tell us the CHEMICAL NAME of the products available to you. Once you have, we may be able to work something out. Include cost info, so we can see what's practical and what's not.

4. Check and see if borax is available, possibly as a cleaner or laundry aid. (Sodium tetraborate *hydrate)

5. Test strips are not -- as you suspect -- very accurate. Tablets can be fairly accurate, though usually not as accurate as a titration.

6. If you are doing color matching, you need to test all your employees for color discrimination. In my work, I found that few staff people were actually color-blind, but that MANY (>10%) of guys were 'color-dumb', in the sense that they'd never learned to pay attention to color differences and so had to be trained to see the different shades. You can get some really nasty results if you have a couple of workers who consistently misread the Palin color blocks!

7. Just to repeat: if you are sanitizing the pool with Oxone (monopersulfate), you are NOT sanitizing the pool!

8. Let us know how much natural light the pool gets: it's very unusual to get algae in a pool unless it gets a lot of natural light.