Hi Keith and welcome to the site. first of all you need to get your water sorted out, topping up from the tap is a big no no in marine, the reason you have brown algea every where is because of the tap water, tap water is full of NO3(nitrate) and PO4(phosphates) and algea will thrive in a tank with any reading of both of them. So you need to find a good source of RO water that has been through a DI resin (RO = reverse osmosis) this waill take out 99% of the impurities in the water, ie Nitrates, phosphates, other minerals, bacteria, dissolved organics and heavy metals to name but a few.

What do you test for at the moment and what are your results?
and what depth is the tank, and are you only keeping a fish/invert tank and no corals?

Regards Richard

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