Bob,

Thank you for the insight. Just what I expected from you (based on what those have said). However, now you have me wanting more...

After some thought, I have realized that perhaps my problem with algae (string in stream and a fine dust-like algae on the bottom of pool) is not the filtration but rather the material causing the wicked chain...excess food, decaying material like leaves and fish waste.

If I have algae growing and clear water, could increasing my filtration actually cause a bigger problem by allowing more bacteria to take up residence in the bio filter producing higher nitrogen levels and therefore creating a greater algae utopia?

I'm sure I am missing something but it appears that the fish (both koi and goldfish) sure have enjoyed this environment because they have successfully spawned numerous times during the second year of having the pond. Many ponds that I have seen on the tour (and just visiting) may have a more algae free appearance (being able to see no algae on the bottom or on the rocks), however should I count my blessings (and those of the parent fish) and leave well enough alone?

Now I'm getting confused. This is such a chicken/egg dilemma. Please help me make more sense.

Rob

The key to fish health in any closed-system pond is excellent water quality. The bigger and more efficient your bioconverter, the better your fish will do. Algae per se is not a water quality issue unless it gets out of hand. All algae are fed by the nitrates produced by bioconversion, and we characteristically deal with two broad types; microscopic floating algae and thread or hair algae.

Algae control falls into four broad categories: Poisons, mechanical, electrical and competitive. Most ponders use a combination of the last three.

Poisons(or algaecides) are available from most pond supply outfits and come with inflated claims regarding their effectiveness and safety. These are all lies. Most of these algaecides not only do not work, but also build up over time to fish-killing toxic levels. They are *not* recommended.

Mechanical removal is simple, and applies to hair algae, which will grow wherever your fish can't reach. The easiest tool for this is a biff brush on a pole. Weekly brushing of clogged areas keeps them under control. A plecostomus (armored catfish) will also keep the hair algae down, and will grow quite large in an outdoor pond. They must be removed and brought inside for the winter.

Electrical removal applies to microscopic algae and is basically a powerful ultraviolet light source placed into the piping just after the last set of filters. It sterilizes any algae that goes past it and prevents the "pea soup" appearance caused by exuberant algae growth.

Biological control affects both hair and microscopic algae. It is simply as much other vegetation, both marginal and aquatic, as you can fit in. When mature, it soaks up a lot of the nitrates, denying it to the algae.

Microscopic algae are bad; an algae bloom can sequester enough dissolved oxygen at night to smother your fish. Hair algae are merely a nuisance. You can deal with it.

Bob Passovoy
President
MPKS