Im hhaving problems keeping my ph up it is at 7.8 my tank is 60 gal ive got crushed coral and live sand substrate about 30 lbs of live rock i run a fluval 405 and a rena xp3 water tests good am 0 nitrite 0 nitrate less than 5 and the problem ph 7.8 the tank is lightly stocked with two baby gsp a tiny lion an angler also tiny and a sf tang baby. any ideas