Old Bulbs = Algae

[Myka]

Originally Posted by MrGoodbytes

Not exaclty the answer to what the OP asked but I thought I would post this for curiosity's sake.

So a peak of 700 nm (very red) corresponds to about 4,140 K.

Thank you for posting this, but it doesn't make sense...? I have some household bulbs that say 3500K on them and they are not red. Am I missing something?

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Chris, the OP didn't ask "why do I have algae?". The OP may not have any algae at all. The OP asked "I've heard that old MH bulbs can be a contributing factor to unwanted algae growth. Could someone explain the theory behind algae growth?" There are nuisance algae threads all over the place (my signature for example lol).