Old bulbs = Algae problems?

[Bryan]

Originally Posted by Delphinus

If I could find a H37 that wasn't also a M58 then I'd just buy it to try it and settle the question in my mind once and for all. Oh well...

According to the Advance catalog, the following are H37 250 watt Mercury vapour ballasts

71A3502,71A3572,71A3592,71A35D2. the difference between the ballasts is whether they are single,tri or quad taps.