These are a couple that I picked up for $20.00 bucks each. They have done o.k under T5 lighting and heavy water flow. I run the lights about 10 hours per day. I keep the p.h. at 8.2 and the Cal. about 400. I don't add anything else just the occasional cyclopeas. I have the in a 30 gal tank. I am not real good with salt water because I just got into it but I must be doing o.k, I have had these now for about a year.