This question was submitted from EMEADS.
“We have a small fish pond which keeps getting an algae build up. We have a pump, biological filter and a U.V.C. light filter. Any suggestions?”
Try these techniques :
The first thing to do is remove excess debris; use a pool skimmer or make a skimmer yourself by stretching an old pair a pantyhose over a wire clothes hanger.
If the pond is really bad you may have to empty the pond and clean. Do this no more than once per year by removing fish, etc., and draining the water and cleaning the pond. Be sure to use a de-chlorinating agent for the water in the bucket or wading pool you use as a holding tank for the fish (use 50:50 fresh water and pond water).
Remove silt and debris from the bottom of the pond (it makes good fertilizer).
If you have plants, remove and place in a shady area so they do not dry out.
Use a brush to scrape down the sides.
When refilling the pond, pour half of the holding tank water in the pond to inoculate the pond with healthy bacteria for the fish; fill the pond and be sure to use a de-chlorinating agent. Be sure to reintroduce the fish slowly by filling the fish holding tank with water of the same temperature as the water in the pond. Fill the 50% you emptied in the pond and empty another 50% into the pond and then fill again so you slowing are changing the water temp.
Be sure to clean the filtration system, usually just by rinsing with water – any soap residue will harm the fish.
Be sure you have removed much of the pond water before trying to net the fish – it will be easier than trying to catch them with the water full.
You should also not clean your pond more than one per year since it take time for the beneficial bacteria to build up.
If you want to clean without going to the extreme of empting the pond then use a rake and pull the debris and scoop it out, but be gentle so you don’t stir up the pond to badly.
The easiest way to keep the algae down is maybe to increase the scavengers in the pond and regular skimming of the pond to remove leaves etc. Snails, mussels and tadpoles all remove the wastes created by plants and fish, inhibiting the growth of algae. A good rule of thumb is one scavenger per square foot of surface.