Clueless.... I'll take a stab at this one.
First off... you'll need a pH meter and a TDS (total dissolved solids) meter. Can't really control the grow without these tools.
Next.... the light may or may not be enough. No way to tell unless you specify the exact light that you are using. The "watts" don't really mean anything. Watts are just a measure of the amount of power it uses. The light spectra is more important. And even if do you tell us what light you are using.... that doesn't mean that anyone has had experience with it. You may be in the realm of "experimentation" (very cool).
The volumes that you specified should be fine. Note however, the less volume that you have in a system will require that you watch for changes more often. Like the pH shift could be drastic over a 24 hour period. Not saying it will....but
Air stones. One per bucket should be enough. You just need to keep the nutes moving around inside of the buckets. It aerates the solution and keeps the surface slime inside the buckets from building up.
The number of plants you want to grow will really depend on the lighting and the nutes. In you case (4) I would just go for it. If the light you have isn't enough, you'll see that fairly early in the grow. You can always add another light.
For the nutes. This is where you'll have to be vigilant and attentive. It will depend a lot on what water you plan on using. You can use TAP water, RO (reverse osmosis)water, distilled water or any combination of those types of water. Fill your hydro system with water, add nutes and grow ! Just be careful of the ph.
You can read further below if you're interested in more specific direction. Otherwise, add the nutes to your system as recommended by the manufacturer of the nutes your purchase. One thing that you absolutely have to be concerned with is the pH of the nutrient solution. No way to get around this. If your pH is out of range, the nutes in the solution will be unavailable to your plants. Keep the pH in the range of 5.5 to 6.5 and all will be well.
So here is more information>>
IF... you are using any amount of TAP water, use your (new) pH meter and check the pH after you fill your system with water. Add either ph UP or ph DOWN (buy these products) to get to a neutral pH of 7.0. Then use your TDS meter to get a base measurement of how many dissolved solids are in your system. This number will be in measured "ppm" (Parts Per Million). Take note of this number as it will be very useful in the future. (NOTE... TAP water can have a lot of dissolved minerals that will affect your TDS readings, so knowing these values will allow you to add just the right amount of nutes to your system).
IF you are using RO or distilled water, the TDS meter will read "0" or very close to it (make sure to actually read it to be sure), and the pH measurements may not be accurate because there are not enough ions in the solution......... ah forget that for now.
Now that you have your baseline TDS reading ("0" from RO or distilled water)(or if using TAP... whatever you measured previously) you're going to add the nutes to the system. I like to add nutes until I get 600 to 800 ppm of nutes. So for RO or distilled water, this means adding nutes until the TDS meters read anywhere from 600 to 800 ppm. If (and I usually do) use TAP water, I add the 600 to 800 ppm of nutes to the previously measure ppm of the TAP water (in my case that is 400 ppm). So I end up with a TDS measurement of 1000 to 1200 ppm total.
Once you have the correct ppm of the solution, adjust the pH of the system to the range I said above... 5.5. to 6.5 using pH UP or pH DOWN. You'll have to check this pH daily until you get a feel for how the system reacts to it's environment. Initially you may not see any changes to the pH, and you certainly won't see any changes to the ppm readings while you plants are small, but things can get out of whack very quickly if you're not paying attention. If you use clear plastic hoses for example, you can get algae growth inside of the hoses that could cause you system to react very quickly. Prolly not going to happen.... but.
pH,pH,pH..... watch this more than anything !
So the last bit I have to say is about temperature and humidity. Unless you live in an environment where the humidity is extremely low, I wouldn't worry about the humidity in the tent as long as your tent is closed up enough to keep some of that humidity inside (humidity from the evaporation of the plants after they get going). The temperature inside of the tent can be trouble though. If you're using your 130 WATT light, you shouldn't have a problem with the temperature inside of the tent unless the temperature immediately outside the tent is very high. If or when you add another light in the future though, the heat may become something to consider. The plants themselves can tolerate fairly high temperature, but when the plants get to the flower stage, high temperatures can be a significant problem.
Good Luck to Ya !!
Happy Growing,
Jeff
