Sounds like a pretty expensive reservoir. And the first step would be to make it *not* clear ;)

What type of hydroponics are you looking at? Since you seem to be new, here's some examples:

Ebb&flood: You routinely flood a growing medium, usually based on a pump on a timer. The flood drains out, leaving damp growing medium. Vulnerable to pump failures. Excellent aeration.

Nutrient film: You have a continuous, but very thin "film" of water running down a gutter that your plants can dip their roots into -- thus getting both air and water -- without any growing medium. Very vulnerable to pump failures. Excellent aeration.

Drip: Your plants grow in a growing medium with some moisture retention capability, such as sand, and soaker hoses keep it constantly damp. Runoff is collected underneath. Minimal vulnerability to pump failure. Good aeration.

Passive: Your plants grow in a medium that has liquid pooled at the bottom, which you replenish from time to time. No vulnerability to pump failure. Moderate to good aeration.

Aeroponics: Your plants hang suspended in a chamber through which you "mist" them with nutrient solution (no growing medium). Very vulnerable to failure. Excellent aeration.

Wick: Your plants remain in contact with a wet wick, which sucks moisture up from a solution below. No vulnerability to pump failure. Good aeration. Water delivery may be insufficient for large plants.

Deep water culture: Your plants are grown floating or suspended over or in a bath of nutrient solution through which air is bubbled. Moderate vulnerability to failure (roots will rot if they don't get air). Moderate to poor aeration. Some plants, like lettuce, seem to love it, though.

So, obviously, there's a lot of variety! Some, like passive and drip hydrponics, aren't much different from growing in soil. Others, like NFT and aero, are pretty radically different. You'll need to choose what's right for you. Whatever you choose, whether you're talking about nutrient tanks or grow containers, you want them to be *opaque*. Light is bad for roots and promotes algae growth in nutrient solutions.

I'll leave recommending particular nutrient solutions to the old timers ;) What are you wanting to grow? Also, indoors or outdoors?

Wow Thank You for all the info I never realised there was so many variations and technic's. I was wanting to try to grow tomatoes now I will have to do more reading to see what would be the best for me to grow. Thank you so much for your help!
Kim

for an entry level tomato system go with DWC. simply paint your aquarium black, put a couple of air stone in it. fashion some kind of lid. cut holes in the top. insert plastic flower pots (possibly drilling more holes in them) in them. put some toms in those and away you go.
Here is my favorite system for one or two plants. its a DWC/aeroponic hydrid. you could modify my scheme to work with your aquarium I suppose. Of course draining the tank will be a pain unless you can install a drain near the bottom.

Water temperature and fouled airstones can be the bane of dwc but its a quick and easy way to get into hydro.

Ebb and flow is a good one for beginners although it requires a bit more kit, a watertight container for hydroton or gravel,a cheap waterpump and a timer..nothing too flash.

Aeroponic is ideal for those that love to tinker with settings and stuff but its also the most expensive to setup.

Actually, the 10 gallon aquarium is a pretty popular entry-level raft system for lettuce. A piece of styrofoam cut to fit inside with holes for the plants works exceptionally well for that.

However, with tomato plants the weight of the plant makes float systems impractical.

First step will be to make the aquarium light-tight. You want for no light to get through the glass. Paint can work but it's difficult to get it really opaque. Look for light-proof contact paper or aluminum duct tape. Cutting corners here can lead to nasty algae growth later.

Next you'll need a good airstone. The cheap stick kind at Walmart are good if you consider them disposable (replace after every grow since they get mucked-up quickly). Connect an air line, glue the stone to the bottom, and glue the line in place up one corner.

Build yourself some kind of light-tight lid for it with one or two openings for a net pot or similar plant holding method. One opening if you're growing most kinds of tomato plants, two if you're growing one of the super-dwarf types. (Only very, very small bred-for-containers varieties will be small enough to fit two to a tank like yours.)

Then you'll just need to fill it with nutrient solution (to just below the net pot or whatever) turn on the air pump, and wait for the 'maters.

Oh, and one big bonus to the fish tank: It's not too hard to find a cheap ice chest (styrofoam or plastic) that it will fit in. That will help you keep the nutrient solution chilled to a nice 63-67 degrees which will maximize your dissolved oxygen and minimize the growth of harmful algae. Just pour some water around the tank and add a little ice as needed to chill things down.