My 125 is PACKED and my water is fine. I have three motoros 8-10", 12" NTT,8" IT, 5" IT,8" cichla, 12" P.Niger, 8" M. irwini, 7" P. costatus, 5" P. granulosus.
Filtration includes Marinland 350x2, Rena XP3, DIY W/D with 950GPH pump, and two internal sponge filters. Turnover rate is about 13x. Im doing daily 30-50% w/c.
Test your tap. The Ohio has been bad lately.