Koi Ponds, UV and Algae

Get rid of dead algae...

News on the Koi front is that summer is here and in full swing. Algae continues to blossom in extra ordinarily large quantities and it's time to talk matters UV.

A UV light kills algae stone dead. How it works is that it ruptures the algae cell wall, which effectively terminates the algae's lust for life. These ruptured cells tend to clump together - due to the stickiness of the cell contents, and it is these large clumps that can be mechanically filtered out of the system.

BUT, and this is a big BUT, dead algae is still very much organic in nature. It represents a significant proportion in terms of overall pond filter load. So if you trap these dead algae cells clumped together in your system, unless you get rid of them they will rot, pollute and poison your pond water as surely as any sludge, slime or rotting debris collecting elsewhere in your pond will.

Removing algae takes more effort than simply nuking them with a UV. And if you have an algae bloom, the resultant load of dead algae in your pond when you suddenly realise that a UV is effective when turned ON, can cause significant problems. At this time of year, with warm water, you need to be backwashing your sand filters (if you still have them) or checking your Answers for clogging more regularly than ever. If you can control your algae growth now, the chances that you will remain stable for the rest of summer (provided your UV is on) are fairly good.

Flow rates through your UV shouldn't be too high. You want to give the lamp as much exposure to the algae as possible in order to well and truly roast it without merely giving the algae a strong 'sun tan'. Slower is better. Even a small mod, involving stripping a UV lamp out of it's plastic housing and chucking it into your primary settlement chamber has been seen to give extraordinary UV performance. Its part of the fascination of Koi keeping there is ALWAYS something new to try!

Koi Pond