Cyno outbreak after changing lights

[mediaone]

It is normal to get an algae outbrake soon after changing lamps or moving to a completely new type (ie. to MH's). However, usually this is indicative of a problem present with the nutrient levels in your tank when you made the switch.

Think of the light as acting as a catalyst to fuel the even faster uptake of nutrients from your tank in to the given form of algae. This is essentially what is happening.

Interesting to note here is that cyanobacteria is not algae, however it relies on similar imputs of nutrients to spread. Once established, it has the unique ability to assimilate dissolved nitrogen from the water, as part of it's tissue! Thus it is important to remove cyano when noticed, and even medicate to kill it if it becomes substantially established. You really don't need more nitrogen input... you have enough in your food!