2pcs 9W 9 WATT UV UVC PL-S9/TUV G23 Base Light Bulb

This is a great value as a two pack. I must admit I was skeptical as I have purchased replacement bulbs in the past and had to send them back multiple times as the bulbs I received were defective. Much to my surprise both bulbs worked. Unfortunately, the head on my canister filter short-circuited and burned out one of the brand new bulbs. I ordered another set and, once again, both bulbs worked. I highly recommend this set.

This is great for your outside ponds to prevent algea growth. I keep it on all yr, all 4 seasons & have to replace twice a yr.

This ultra violet lights work great in my pond . Definitely does the good. Easily to install, lasting and very long time. As in more than a year. Continue to buy

Building quality is decent, but these UV bulbs work well. I cannot comment on longevity because we have them near an HVAC heater core where they are exposed to rather high temperatures. Overall, I'm happy with the purchase. Just be sure to clean them with rubbing alcohol and handle them with gloves when installing. I've found it best not to get skin oil or fingerprints on them, as these might cause bulb failure when used with long cycle times and / or in a high temperature environment. Another thing, be careful not to look at the light from these bulbs or let the light contact your skin, as unshielded UV-C can be very dangerous to eyes and not too good for skin either.

These bulbs fit my pond clarifier so have no current complaints. Time will tell how long they last. Much cheaper than at the store so recommended so far.

These actually worked great, but unfortunately my filter pump quit a few days after I bought them & I changed to a filter that takes a different light.

Burned out quickly

Great product at a good price. Fast shipping