Its due to the fabric pots. The air exchange is 360 degrees so putting the bottoms under water leaves a lot of air gap in the side walls still.
To be honest, bottom watering makes watering much easier, sort of, and is definitely extremely compatible with aero-clones, but at the end of the day I see no difference in the overall plant.
The roots look different but thats understandable as the plant adapts to the location of the water.
I say "sort of" because I use 1/4 gal/hour dripper heads (4 per pot) when I top water and they are on a timer to come on 3 times a day so I have no wet/dry cycle when I top water.
I still haven't tried a true SIP yet so my mind is still open and I truely hope a sip will outgrow my regular routine and the swicking with perlite, but to be honest I don't see how a salad strainers worth of air intake can out perform a cloth pots air intake.
I think sipping looks dramatically better if you are a hard pot grower but not if you are a cloth pot user with a watering routine that keeps the soil evenly moist constantly.
I will be starting some Durban seeds in the next few days, I just have to see what the calendar tells me for a start date, and I will use a hard sip pot vs a 10gal cloth pot in perlite and we will see. I truly hope the sip will do better as better is better, but what I really want is a way to start a seed or clone directly into its final pot to avoid transplant shock.
My biggest problem is when I grow from seed my plants get way too big in the 56 days of veg, so having a plant that grows faster in veg really only causes me grief.
Don't get me wrong here though, bottom watering ensures a gradient that is pretty much perfect, and eliminates runoff that removes calcium and other nutes, so its better. Remember my runoff testing earlier? 1365ppm. Thats a huge waste.
If you haven't truly figured out top watering then its light years better.Period. If you are a new grower that isn't interested in science and only wants yield-with-ease then its the way to go. If you are using hard pots and top watering then switching to sip/swick will truly rock your world.
I'm not arguing that and I will continue to use it, but I suspect the life-changing results are for hard pot growers. Smart-pot growers already experienced that when they switched to cloth.
I think your idea of a soil sip pad to place a cloth pot on is what will prove to be the very best, as it gives you extra soil, but the proof is in the pudding.
Perlite beds work pretty darn well and you can see the water level thru the tub so you can tell exactly how much water was used and literally watch it go down which if you pay attention, and I haven't yet, but I will, will tell you exactly which part of the daily life cycle uses the most water. Knowing that will really help if you are a synthetic user as it would tell you when to feed and when not to feed.
Ph changes in synthetics so feeding when the plants aren't eating won't give you the correct ph a few hours later or possibly the next day when they really start to consume, or they may have a constant intake all day long and it doesn't matter.
Bottom watering has already solved 2 of my major hurdles. I can clone directly into a 10gal pot now with no stall or babysitting/spoon-feeding (I actually see an acceleration) and I suspect my 1.6 gal pots will go farther than they ever have with there being no runoff, so bottom watering is definitely better, but the overall health and what not of the plant itself is pretty much identical to my previous grows.
I have had giant featherduster bags of roots ever since I have switched to cloth pots. I will know for sure on a Durban grow as I know the strain intimately.
I will readily admit though that having to move a 10gal pot with a bed of perlite really really sucks. My pots with the perlite are probably 80 pounds each so thats a contentious issue, but now that I know I just need to plant the clone with the pot in its final resting place.
Overall bottom watering is way easier and extremely consistent, and I greatly suspect my soil will go a lot farther, I just don't think I will see a giant explosion of growth, I got that in 2017 when I switched to cloth.
But fingers crossed
, I love it when I'm wrong