Perlite is often used in a 50/50 mix with vermiculite or peat moss, or even coco. There is a fine mix of perlite for those "small cups" that are commonly used with deep water (or for seedlings), and more coarse (8mm) for the use in bigger buckets and pods. Be sure to have the right-one for your use.

I was quite interested in this media first, because it seemed kinda high-tech. But was somewhat disappointed when testing and using it. It sticks to your fingers like hell and attracts more algae then any other media. In my view it is over rated and only popular because it is well promoted by it's manufacturers. Personally I only recommend it (fine) in a 50/50 mix with vermiculite (with some 10% coco, to retain more moisture). Wether for deep water salad or for seedlings (without coco for deep water and with coco for seedlings). Although it is still the perfect choice in soil media (peat moss, turf- or other substrate based products) to assure a good drain (but 6-8 mm coarse in this case).

I grow in 100% perlite and the key is to use only the large size stuff. The fines will drive you nuts, clog things up and make you wish you were a dirt farmer.

If you want not to water as often, plant your tomatoes DEEP in a very large container. I have several growing in 30-gallon plastic trash cans that have broken bottoms. Not so good for trash any more, but great for drainage. I place a piece of nylon window screen over big holes and water until it starts to ooze out the bottom onto the concrete greenhouse floor.

I buy my perlite directly from Aztec and enough to fill a trash can costs around $4.00

I never thought I'd admit it, but having considered static culture the "ultimate" in hydroponic growing, I've changed my tune and now use aeroponics. It's a little (well, a lot!) more complicated, but stuff grows like magic!