Thank you Evelina, The law is clear - the Landlord has 15 days to return the deposit or file a claim, then tenant has 15 days to contest, but that does not answer my question.

My question is: If landlord sends a letter within 15 days claiming this and that (99% regular wear and tear), put prices for light bulbs and some other things, but keeps the amount open for "he does not know the prices yet" - so could be $300 or $ 3,000 .... Is that legal? if after 15 days he does not have a claim to a specific amount, does't he lose the right to claim at all?

Section 83.49, 3(b)(c), F. S.
Unless you object to the imposition of the landlord’s claim or the amount thereof within 15 days after receipt of the landlord’s notice of intention to impose a claim, the landlord may then deduct the amount of his or her claim and shall remit the balance of the deposit to you within 30 days after the date of the notice of intention to impose a claim for damages. If you object to the landlord’s claim you may file a complaint with the Department of Agriculture and Consumer Services or institute an action in a court of competent jurisdiction to adjudicate the landlord’s right to the security deposit.