28 Gal DT, 50ish in total with sump, 4.5Gal ATO. I usually top my ATO up every few days, not cause I need to but if I ever have to do a quick WC I already have just about 10% of my WV ready to be mixed. I don't have room for large storage containers yet so it's a good alternative until I start mixing my ATO with Kalk.