Any Disadvantages to Using Pond Colorant?

[elizabeths]

Hi Guys,

Quick question:
We have a UV filter to keep algae down in the pond, but we still get darkish water. I'm thinking of trying a pond colorant to help keep algae down further. Are there any disadvantages of using a colarant? thanks!

 

[koidaddy]

I used it last year and found the only issue was it stained the rocks some but that has since cleared up.