We manage a property that was having drain field issues for awhile, got estimates and had the owner approve one of the vendors.

I'm hoping someone could explain to me what this means on the HUD Property Condition Report - pour water/antifreeze in drains - fail.

The water may be backing up from another fixture that is not draining properly.

That's SLOW - but effective. 

In other words, if you don't fill your unit in the slow season because you're afraid it will cut into your high season revenue, will the high season revenue more than cover the difference?

(It costs 10k+ to drain, clean, refill the pool so I only do it once an year and this is pretty standard) I think it is matter of if it looks dirty or smells bad when guests use it.

If you have the electrical capacity and the drain I would spend the $1600-$1,800 to buy the MUCH nicer ventless GE or LG all in one units.

(Previous rent was $1,300 but we're about to put in a brand new kitchen from the studs, new flooring throughout the house, new furance, adding A/C, etc).So do we just pay for it all upfront and mostly drain all of our savings, or do I let the rent pay for it and utilize our other savings to get a second property this spring/summer to increase our cashflow? 

Most won't insure pools with diving boards or ones without a VGBA drain.2) Include the cost of a pool company to manage the pool in the rent. 

Imagine investing in all new, beautiful finishes, only to discover that the drain pipes are faulty and need to be replaced—an issue that could have been identified and addressed beforehand.