When troweling the sand or vermiculite pool base, a minimum of thickness of 1½" must be maintained throughout. Spread the vermiculite out with a flat shovel into roughly 2' X 6' sections. Use a 30'' magnesium Darby or 16" pool trowel to spread and flatten the sand/vermiculite. Get the vermiculite as flat, even, and smooth as possible while spreading the material in several directions.
At the base of the hopper walls, bring the sand/vermiculite 2" up the pool wall to the set string. It is important to avoid sharp edges or pockets in the pool bottom, thus avoiding areas for dirt to collect after pool is filled. Make sure everything is spread until smooth and even.
As deep end slopes are completed and the hopper bottom is troweled, all strings and stakes should be removed from the bottom and vermiculite troweled smooth. Be careful to trowel out any crumbs as work progresses. These will show though the liner if they are not removed. If the bottom is troweled from deep to shallow it may be difficult to keep crumbs out of the finished bottom. Debris cannot be swept out until bottom is cured, and most vermiculite mixes are not ready to walk on for at least 24-48 hours, delaying liner installation.
If troweling shallow to deep, keep working crumbs and debris to a final corner of the hopper. Trowel the deep end walls first, the floor around drain, and work your way onto the ladder board. Leave the pool carefully to avoid crumbs and carefully lift out the ladder and board with two crew members.
Starting in the hopper end, bring the pool bottom up to finish grade with a damp-sand/cement mixture, or vermiculite/cement mixture. Trowel smooth.
Wipe the walls clean, check the pool bottom for stones, twigs, and/or sharp objects and remove them.
After the bottom has been completed, the liner can be installed on a wet or dry pool floor. However, if weather and time permit, allow the pool floor to dry completely (24-48 hours).