Lumpy engineed Resin

I have a problem with engineered resins Tough1500 and Durable. Both afterr a dozen resins need to have the tank cleaned and filtered as the resin is no longer a consistent liquid. The liquid becomes so heavy it stops the mixer working.
Solution Do i have the room to hot? The room is around 15c to 23c in temperature
Does the ipa cleaning fluid contaminate the resin?
Needs better protection from sunlight

Any ideas please

If you ever had a print fail, that failure left debris in the resin tank. If you didn’t filter the resin after the failure, that debris will cause additional failures and more debris. You need to do “preventative maintenance” on the resin periodically, unless you are 100% certain that there has never been any kind of print failure.

The orange plastic cover blocks UV, but if the printer is in direct sunlight, that’s still bad. And of course, any time you open the cover the resin in the tank is exposed to whatever UV is in the ambient environment. If there’s sunlight shining on something nearby, that’s likely to reflect UV on to the resin tank and start curing your resin.

Also, regarding your question about IPA. How are you getting IPA in to the resin tank? That should not be possible if you are using the printer the way it’s supposed to be used. There’s no chance of contamination if you aren’t introducing IPA to the resin in the tank. If you are, then you should email FL support to discuss your workflow to figure out what you’re doing incorrectly.