More oxygen in the rootzone = bigger yields. Watering more often does that. Draining to waste when watering several times a day to achieve that aim is 'waste'-ful. Veg growth especially is noticably faster. Also when managing a res that is only topped off and never totally emptied allows cultivation of even more beneficial bacteria than normal, either you see the benefit in that or you don't, not critical IMO because there are already bennys in the medium. If you are trying to get the yield benefit of multiple waterings per day without dumping alot of expensive nutes down the drain...recirc.
Refer to above....also since coir has a near perfect water/air ratio, soaking wet or dry it still has enough oxygen, hence your big yields when not recirculating, but then adding more oxy makes yields/speed of growth that much better. Like i said above coco is not black and white and by no means do i say that handwatering is not any good, just that recirc tweaks an already good thing. That comparison above to soil is innacurate, coir growing has a different set of rules all its' own. I used to think coir was too wet, even after reading alot of factsheets that mentioned that perfect air/water ratio, and reccommended eveyone add perlite lol...while also watering on a wet/dry cycle like in soil. The results are good that way but as Gauis has said the true potential of coir can't be seen until you treat it like hydro.
Agreed...filter the drain that goes back to the res...problem solved, fine coco can be a biotch though, IMO it has less oxy, but I don't know that for a fact. Here's another con: multiple waterings per day tend to cause mold on the top of the medium under a thick canopy/low light....add enzymes which you should already, put single strip floros or CFLs near soil level.
