The key to keeping your temps down is moving air through the grow space. Ice not only will be an impractical mess but would increase humidity- something you're already going to be contending with in FL.

You need to maintain the grow at about 80F or under. With sufficient airflow, you should be able to keep the op no warmer than the air that is being drawn in. If the air that you draw into the op is warmer than that, I'm afraid air con is your next option.

Flowering lights-on should be done at night to take advantage of cooler nighttime air to pump through the grow.