Amount of skimmate from skimmer

[Baldy]

Hello all, I have a question.

I have a Tunze DOC 9006 skimmer on my 75g w/ 20g sump. current tank inhabitants are 2 ocellaris clowns (1.5 and 2 inches), 1 blue green chromis (2 in), 1 flame hawk (2.5 in), and a one spot foxface (4-4.5 in) as well as CUC and coral. as far as coral, mostly softies and LPS, zoas, tons of kenya tree, mushrooms, rics, candy cane, hammer, blasos, i think thats everything.

My skimmer seems to not be putting out much skimmate. i get maybe 20ml per week if i clean it twice. it seems to skim good for a coouple days then peters out until the collection cup is cleaned again. I dont have any issues with nitrates though. I just finished a check with a new API test kit, and theyre undetectable.

is the low amount of skimmate due to a low bioload? or should i not be worried about this at all?