If I were you, I would buy some 8 cent goldfish or catch some local bluegill. You already bought an air pump, you might as well get some fish, because that is what air pumps are for. Cheap plastic bins work fine for tanks. Then you can use the water from the fish tank to put into your hydro reservoir. The tiny amount of nutrients the fish provide are not the reason - it's the bacteria that you're after. The bacteria that eat the fish manure at the bottom of the tank are beneficial to roots. And they only cost as much as the fish food.

General Hydroponics nutrients are probably the most common brand. They are easy to use. Organic nutes can be clumpy and clog your lines; filter them before using. Your ph will depend upon the strength of the solution and the ph of the starting water. GH makes a different formula for hard water. Filtered water is good; reverse osmosis is the best. But filters cost more than goldfish.

Are you using that system indoors, in a greenhouse, or in the sun? The weakness of that system is the hot sun making the roots get too hot. Inside, climate control is easy. For a greenhouse, you would need the appropriate shade material. Burying the reservoir helps a little. But if you were to set that system up in full sun on a very hot summer day, the roots would rot from getting too hot.

Thanks for he advise; didn't realize heat would be an issue. I was hoping to get in a crop before it gets too old here in southeastern Pennsylvania.
I doubt I'll use it during the heat of summer; My regular garden is in full swing by then.

Here is a link that might be useful: The Prudent Gardener

Once you enjoy the benefits of hydro, you'll abandon your soil garden.
The best way to limit heat gain is to put aluminum across the top of the system. Aluminum not only blocks light penetration it also reflects radiant heat.
In PA, heat won't be much of a problem if you simply set the system to get full sun from early AM til just after noon (maybe 1-1:30) as the hottest part of the day is after that time. I live in NC and don't have too many problems with the sun using that method.