I dont think it`s too much. How long are they on during each day? Another problem is when they talk about lighting they are talking about older lighting. The older a bulb goes it`s spectrum will shift causing algea to feed off the different spectrum. If for example my VHO
`s are supposed to be changed every 6-9 months and I wait and still have the same bulbs in there after 1 1/2 yrs then the bulbs are too old and have probably had the spectrum shifted. JMO. You keep using that FR formula and you`ll be OK on the nuisance algea.