Question
After trying everything I can think of to deter algae growth in the bowl of my backyard fountain, I have tried white vinegar in the water.  It seems to help very well.  Do you know if this is safe and do you know what proportion of vinegar to water should be used?  Thanks for your help.  jr

Answer
I assume your fountain has no plants or animals in it?  Do birds or other animals drink from it?  You have a few options.  Vinegar and stronger acids and bases will deter algae but, in high doses, are not safe for animals to drink.  How much vinegar is needed to keep the algae badk would depend on the light levels there, your water's pH and buffering capacity, how often you change the water, etc.  

There are some "fountain clear" type products out there that may work for you.  Some are pretty toxic but others are all natural bacterial mixes (may not really work for algae though but they say so).  In my fountain mosaic tub pond where I have no plants or animals, I use a product called Algae-Fix by Aquarium Pharmaceuticals.  It doesn't take very much, and it really keeps the algae away.  Best of all, it's not toxic at normal doses to plants or animals (except for shrimp and other micro-life).

Robyn
fishpondinfo.com