There's a learning curve with the chibi but it's a short (and easy) one. My first one flooded too but I think it was because I wasn't careful and nicked the grommets. This second one is working perfect and when I get my replacements in, I can use them on the other polycarb sheath. (I hope they fit). It's ALL about air pressure and equalization of air pressure. when filling, you MUST be careful when sliding the needle down beside the grommet and you must tilt the needle a bit to let air escape while you're putting
juice in the tank. It's not hard at all once you do it a few times. That said, I believe that each time you (I) refill, there may be tiny damage to the grommets that add up over time. And once enough damage is accumulated, air will be able to get into the tank and it will keep flooding. But that would fall under the heading of "normal wear and tear". These are cheap enough to buy new ones when that happens or just get some replacement grommets (please let me have ordered the right size!)
I like things that are inexpensive, simple and easy and I work hard to research the right products that fit this criteria and will work for me. Chibi tanks fit that bill. I never was too interested in tanks because of the price. $25 is too much for me to spend for one just to try out. I've got bottom feeders so that too was a factor in my disinterest. But tanks are so much easier and simpler to use. I don't worry about squeezing the bottle and I only have to fill it once a day. Plus, pared with a bottom feeder, I don't worry about running out of juice cause I have lots on top and on the bottom!
When the tank is filled and working right, I can lay it on its side, throw it in my purse and vape laying in bed. I've found that if it's going to flood the carto, it will do so right away and once the air pressure is equalized I'm good to go and can lay it around any ole way.
Something else I've just discovered. I was using the tank with a 1.7 resurrector on a simple 3.7 device and it just wasn't hitting hard enough for me. I found an adaptor and now I can put it on my vv device and with the voltage turned up to 4.2 and it's hitting much better, the draw is less airy and it's as close to the perfect vape as I've some across yet.
Before I found the adaptor, I couldn't use it on my vv box because the catchcup didn't allow me to screw the tank down far enough to make a good connection. I'm now starting to look at vv tube mods because I've found a way to feed the carto without all the constant refilling/topping off.

Tanks have opened up an whole new world of
vaping!