I would replace the UF ...

I would replace the UF filters altogether with an Activated Filter Media which will last over 20 years as it is self-cleaning, self-charging and self-sterilising filter media. It won't clog up because it is an electro-static filtration method rather than a physical barrier. Biofilm will not grow on the surface of the media bed to clog it up either. At my company, we typically use this as pre-treatment to any ro or uf system to protect the membranes.

In terms of algae control, you can manage this with mechanical aeration, I have experience in reducing algal counts of 1.2 million to less than 80 using fine and ultrafine bubble aeration here in Australia. Passing the water through a static mixer will raise the oxidation potential up to 200 mV to help with oxidation. This will also result in intense flocculation to help pull out the dissolved organics through the hydrodynamic cavitation reactions.

If you would like to know more, please email me at andrew@waterandoilsolutions.com.au