[schildkoi]

One of my favorite subjects....and one that is not totally understood by many. The replication rate for unicellular algae is dependent on nutrient levels, temperature (water) and sunlight (duration and intensity). Other factors also come into play on a minimal level as well (minerals O2 saturation etc). When the combinations (infinite) of these produse a replictaion rate greater than the die off rate, green water exists. UVs address the die off rate but do nothing to reduce the replication rate.

Equal systems (pond designs) can yield differewnt results in different climates as well based on the water temps and avauilable light. Thus MikeM's comment about shae (which reduces water temp and available light) comes into play.

One thing we typically hear is the amount of filtration. Keep in mind, a filter with "2X" surface space/efficiency can be no more effective than one with "X" if "X" is already efficiently processing the all nutrients being supplied.

Thus, the turn over rate (or amount of nutrients being fed through frequency of such) is typically the "forgotten factor." by increasing the filtration AND improving the turnover rate, the ambient nutrient level is reduced which in turn lowers the replication rate of the unicellular algae. This not only helps to improve clarity, it has the even better result of improving the QUALITY of the water. Remember, clear water is not in and of itself a measure of water quality.

Steve