Since my subunkins/koi/sarasa comets are in BLACK, above ground stock tanks of 100 and 150g capacity on the SOUTH side of the house, I do have some concerns there as I've been running them with no filtration other than live plants. When it's in the 90's, I tend to need quite a bit of water for my outside plants, so every afternoon I put the hose in each stock tank and run new water in and use the overflow to fill ~ 30-40g rubbermaid containers. Those are my watering tanks....I use 3 g buckets to walk water to my fruit trees etc. It's lots of work but hey, it burns calories (grin). Eventually, I'd love to be able to provide mechanical filtration but I have no external outlets on that side of the house. Betty Goetz _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member