The lockers at Manta have no time limit, but are one-time-use. At Manta there are two sizes... small lockers are $.50 and large lockers are $1.00. There are also one-time-use lockers beside Kraken (small and large lockers) and Journey To Atlantis (small lockers only). You will not be able to take any bags or loose articles with you on the rides (or in the line).
Hope that helps!