Change your bulbs. As they age, they produce too much red-spectrum light.
Make sure you are using RO water in your tank. Tap water can contain phosphates.
Buy some golf-ball size snails
Remove it the second you see it (I find a turkey baster blows it off in sheet that can be scooped out with a net.
Increase your water movement. Add another filter at the other end of your tank or use a power-head and wave maker.
Buy some calurpa to out-compete the slime for nutrients.
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