Looking for helpful advice an opinions, so far I have had so much conflicting information thrown at me!
18 months ago I drained and enlarged a lake. It is now 150m x 100m with an average depth of 4m, with some parts as deep as 10m. The soil all around is a sandy clay, and at the moment at the bottom at the moment there is around 20cm of silt. There is virtually no vegetation around the outside of the lake, no animals and there are no fish in the lake whatsoever. The lake itself is filled by an underground aquifer and run off from rain water. The temperature here in Thailand is generally around 30 degrees celsius.
The water colour is a stunning blue colour and after testing visibility both underwater and with a secchi disk provides 6m of clarity. The water chemistry i have determined thus far is pH 4, KH 17.8, GH 890, Nh3 0, NO2 0, NO3 0. So, very low pH, low KH and very high hardness.
The aim for the lake is to use it as a floating water park, so there will be people swimming in the water. I absolutely want the water to be devoid of any fish. Clearly for this to work as a water park and be safe for customers I need to ensure that both biologically and aesthetically good. I don't think filtration on such a large body of water is particularly viable, but I was thinking of the following steps:
1. Dig a berm around the perimeter to control run off during rainy season, treating with gypsum before it runs back into the lake
2. Adding chlorine to the water to maintain biological cleanliness
3. Adding gypsum to the lake on a regular basis to keep the TSS low
4. Making a sand beach around the perimeter (this is nice for customers and will help with some basic filteration)
Sorry for the long post, but I would really appreciate comments, suggestions and any ideas you might have. I have enclosed a picture of the lake.