Blinds 5/5

4 limpers, I am in sb with AsJsJc7d5h

Flop: AdKs3s

I check, bb check, utg+1(800) pots to 30, middle(500) calls, I (420) call

Turn 6s

I check, utg+1 checks, middle bets 90 into 120

I think middle (tight passive) has "always" minimum the NL here.
Utg+1 (loose passif) has AK, KK, 33, 245, I'd guess.

1) I don't know if I should repot or call to let utg+1 call as well.

I call, utg+1 calls.

River Kc.

2) what should I do now? I may be the only one on the high since utg+1 should fold his high only hands on the turn. He could still have AK24 or AK25 because he's passive preflop or 3324, 3325, maybe even KK.

I opt to check, utg+1 bets 170 into 390, middle calls.

3) what should I do now?
I represent the nut low, so I don't understand his betsizing.

You're against one NL, possibly two with a mediocre high. No re-raise on the river and UTG+1 doesnt show very great strength if he has hi boat and NL.

Call is easy, but a re-raise might be the right move for best value.

There are nut lows and full houses in the same hand out there.

Probably a river call, but think re raise is too optimistic.

You don't think the full house raises on the river? Hero played it like they had the NL, so mid position 'should' raise the river based on the action even if the river gave them 6s over Ks.

1) I dont think Im repotting on the turn. We arent scooping this pot, and according to your range, UTG+1 has a small amount of equity. Folding him out still leaves you getting free rolled by middle if he minimum has nut low. With the range provided, it seems like it would probably be incorrect for UTG+1 to call the turn behind you. I would call and give him a chance to put it in bad. Is there a chance he has a low with little spades? That would help the case for flatting the turn as well. Unless you feel raising could fold out both I think I just call.

2) I check here. UTG+1 probably "should" have folded the turn but do you think he actually would? You mentioned he is a loose passive. I think he easily calls with his high only hands but I could be wrong. Maybe the games I play are far different (fwiw I mainly play PLO8 MTTs).

3) I was leaning fold, but then thought maybe that was due to a tournament mindset that has to consider stack preservation. With the information and ranges provided, it appears there is at least one nut low (middle almost certainly) and a likely boat. If there is a chance UTG+1 bets river with trips and nut low or nut low and small spades it could be a call. However, the action sure looks like UTG+1 flopped a set or top two when he pots the flop and checks the turn. Is a fold awful here?

I don't have a ton of Big-O experience, but in the little I do have it appears to be a game of the nuts. Both players were described as passive. I dont think they are betting just nut lows into each other on the turn and river. It looks a lot like a full house for UTG+1 and at low for middle. Who knows, maybe I'm just seeing monsters haha.

First of all, raising the river (yes, raising, not re-raising as nobody has raised yet) is borderline ******ed. You are pushing a lot of money into the pot with a marginal hand. I think you should call but obv expect to get scooped a lot (by AA/AK/KK).

Turn obvious call, raising doesn't make a lot of sense. River obvious check.