I too live near Mabprachan Lake and have a similar situation.
Around 4yrs ago my pool was re-grouted with what I was told was top quality grout, but after only 4yrs, the water had completely destroyed 100% of the grout and began eating away at the tile adhesive, resulting in tiles lifting all over the pool.
I decided to re-grout the pool again, but this time I did the job myself using Weber grout and replaced or re-laid the tiles.
This done, the pool was re-filled with crystal clear government water delivered by tanker.
As the pump was also leaking, I attempted to carry out repairs to it, but couldn't get the correct spare parts and as a result, the pump needed to be replaced as it wouldn't even self prime any more.
A complete pump and sand filter were ordered, together with Zelbrite media but this took 12 days to arrive, by which time my pool had become a lovely shade of dark green.
Since then, (2 weeks ago) the new system has been running for 18hrs p/day and although not green any more, the water is still cloudy and despite chemicals being added every few days by my pool guy, it is not improving.
Standard test kit shows PH way too low and Chlorine does not even register on the scale.
Having done some research, it would appear that you need a more comprehensive test kit and a good knowledge of the myriad of chemicals that may be required to correctly balance the water.
If anyone knows of a competent company in my area that could carry out this exercise, please let me know.