Well since you ask there's a couple ways to do that too.....I found the best way (since the pics are there) was to set it up on a timer so that once every few hours the entire system would recirculate. The stop valves are all set in the on position generally unless I want to change something.

In the pics above the scenario goes like this....pump turns on and runs for two minutes. In that two minutes it pulls all the water out of the buckets and sends it to the top rez.
The pump then shuts off.

Because I've set up the tubing from the BOTTOM rez to the buckets in a VERY meandering style with a bunch of L turns AND because the system fills on gravity the refill is extremely slow. The water follows the patch of least resistance.....so with a (pretty straight) line from the buckets to the pump your chance of pulling out NEW solution from the line instead of what is in the buckets is very small. The timer is set up to run four times a day......every six hours.

I dont know if this will work for you with your 8-16 buckets so daisy-chaining them with a circulating pump may be a better idea for you. X-Crispi uses the very small pumps (120 gal/hour I believe) and he would put them inside THE BUCKETS themselves. But again......you'd need an entry AND an exit hole in each bucket to work with.

Is it worth the work and expense? Yes..I think so. It will help a LOT keeping your ph stable in general as it tends to rise during flowering at a fair rate. This is normal and once the plants get big....trust me.....you WONT want to be adjusting the ph's one by one. It will also help keep your nutes ratios in balance and provide better 02 saturation in your water.

Keep in mind that it won't solve ALL your problems......it will have it's own drawback and "side effects" you'll have to monitor but it's better than the check-one-at-a-time buzz kill. :jointsmile: