Tank will be HDPE so most glues & fillers will not work
Get some HDPE filler rod and weld the crack using a brand new soldering iron tip or hot air gun.
Note the surfaces must be KLEAN with a capital K.
Hundreds of vids on tank welding but the magic word is clean.
When any clean plastic surfaces come into contact & are heated they will weld together.Down here is use plastic milk bottles and a hot air gun.
Done dozens of JD 100 series tanks.
Once you put any goo on the crack it can never be welded.
If the JB does not hold then you will need to cut all of the JB out and fit a patch piece which is a lot harder than welding the crack, filing it down then covering with a piece of milk bottle.
Your tank so your decision.