I keep my Dionaeas, Cephalotus and Sarracenias in trays of water which have become contaminated with some sort of green algae. Draining and refilling the trays doesn't help because the stuff always grows back.

Is there an algicide available that will not harm the plants or the live sphagnum that they are potted in?

Hi Mcz,

'Fraid algicides are probably out of the question. This page from the CRC for Water Treatment and Quality lists currently registered algicide groups:

http://www.awqc.com.au/NR/rdonlyres/575D5A7E-8A24-4B43-AF7F-A2F700A9FBE9/0/Using_Algicides_in_Australia.PDF

Algicides are tyically copper sulphate type chemicals that are highly toxic to mosses (and usually used to kill mosses). The only other type listed is classed as a broad-scale biocide (ie. killer of all living things), so I would avoid it as well.

I've had good results by using deeper than normal trays (eg. kitty litter trays or foam broccoli boxes cut to no more than half the height of your pots) and filling all gaps around the pots with a small, rough-edged gravel. Don't use anything that is porous or absorps water. Drill a drainage hole in the tray so that the maximum water level is as high as possible without beeing seen under the gravel. Fill with water as normal.

This method is excellent at discouraging both algae and mosquitoes in CP trays. It was used by a number of nurseries that sold carnivorous plants from Geoff Mansel & Geoff Robert's venture G&G Carnivores, so it may have originated from them.

Hope this helps.

Regards,

John in Canberra.

My blog

I would tend to agree. John's suggested method works very well... the problem with algicides is that, since algae is a (rather primitive) plant, anything which kills algae will probably not do your plants much good...

It is also good practice to dump out and clean the water trays periodically - this helps control mozzies as well.

Thanks; I'll try that.