i want to use a 20 gal tank just below my 35 gal is it possible to use a power head 802 to return water to tank once it has gone thru filter material. i would also like to know if i can use another power head to pump water down to filter without pre filter just connect hosing or piping to powerhead to flow down to filter, i want to situate 20 gal about 1 foot under 35 gal.any suggestions i'd appreciate.