UV Flow Rates - Why Such A Big Variance?

[RMS18]

I plan to add UV to my system mainly for water clarity, cutting down on carbon cost. I used to run a small 10w on a 30gallon I had back in the day and loved it. I forgot what flow rate I ran it at and why.

After looking at BRS they stated for a 25w 79gph to 133gph. From Emperor.

Aqua Uv states 1200gph to 800gph.

Aqua uv states using at a lower flow will destroy the planktonic food supply for the reef.

Obviously for all the bad they kill they will also kill the good. But how much of an impact could that make killing some good? I would say you have bigger issues if a UV easily crashes your system.

I use to also run it only 12 hours a day, something I may do again but trying to figure out the flow rate for pump purchase.

 

[vangvace]

There are small design differences like bulb, sleeve, and chamber sizes. That said, brs' recommended flow rate in their write up is the "kill all the pests" rate versus the 472 GPH/788 GPH recommendation for algae level sterilization. Aqua UV flow rates for the same "kill all the pests" level as the one sold by brs isn't listen on their µw/cm² charts, but would be similarly slow.

As silly as it may sound, you could use an example of chocolate melting in your hand. A milk chocolate square (algae) will melt quickly if held. Dark chocolate takes longer to melt and M&Ms (protazoa) even longer.

I would also caveat that you likely do not have free floating plankton food in your tank. brs should be posting a video Friday on different flow rates through uv. It covers control, live rock, and dry rock in regards to algae I believe.