hobbyist knows best
.... niko is right, i took his advice and it has help, i have a eheim rated for a 66 put it on a 60g tank and had problems. but i cut it half and put it on a 29g and it was perfect.
i think canisters don't get rated right. we never think about returning head volume pressure from the pump and how it loses pressure the higher it has to return.
I like DNA, but I'm not sure if you got the right stuff you needed.. and as nikolay said i would do bigger more frequent water changes....