Do you have a reef tank with the cuttles in it? Phosphate test kits arent very accurate, I think they are within .3 , so in an sps reef tank - if you have a positive result (ie not zero) you have a problem.
With those phospahte removers - do they last forever or do they need replacing? I know that apparantly some nitrate removers take out phosphates too - and they pretty much last forever(if flushed out once a year or so).
How good's your skimmer? Most of the high phosphate problems come from not enough skimming, or overfeeding. Dirty rocks can be a problem too.
Is your system newly set up? If it is the rocks could be doing the shedding thing, and youll have to wait till their phosphate stores are emptied and the system stabilises.
I would imagine cuttle fish arent the most discerning choice for the phosphate concious.
EDIT:, as Dan says above , tap water high in phosphates is another common cause of problems. Most town supplies would be high in Po4.