I see, to be honest I have not checked how clean it actually is. It is visually transparent, as opposed to the used one, but you are probably correct.

What I do is just expose the dirty isopropanol to sun or UV in general - the resin will precipitate. Then just filter it out and you have clean isopropanol.

It’s absolutely not. Median is a value in the middle of a sorted set and average is, well, average. In the set of 1, 7, 10: 7 is median and 6 is average.

They look like air bubbles to me, but it is weird they only come out after the bath. Could be they were already inside, but only covered by a thin wall of resin.

I usually use Isopropanol for bath not Ethanol, so I am not sure how your resin reacts with that. The bath should also be rather short, like 1min or something.

A few things to try:

• If you are shaking your resin before print, then give it like 10 minutes after you pour it into the vat, so all bubbles come out and pop
• lower the print speed
• add wait times between the end of lowering the plate and light on
• try to hollow out the model if possible, so there is less printing volume