22x52 ultra frame 2500 gph bbb method tf100

Looks like i have a drip coming from behind where the intake valve screws onto the pool from the outside looks like their may be a tiny amt of seam that isnt entirely covd by the outsde screw down part. Noticed it yestrday took but tighten the screw it stopped now its back and ive tighten all i can..is there anything i can use to perhaps place in that seam...a caulk of some kind?

Also i need to drain quite a bit of water to be able to use the intex hose vac which is all i Have. My son dumped alot of dirt in with a pool toy by accident. Vac last night with stocking it worked thank u for that advice i got here but now pool is to full to vac again.