For Guarantee I think in the way David your thinking about Guarantee the only one out there is FDIC insured deposits with the full faith and credit of the US Gov. 

An estoppel certificate is a form you have the tenant sign that confirms their lease start date, the amount of their security deposit, and other things.

Also, tomorrow I will be requesting a Deposit to Hold of $500 which will add to their legitimacy.

How should the security deposit be managed in this transition?

Do you have to keep the security deposit in a separate account?

So there is just not that big of market for all these people that think they are going to loan EM deposits. wholesalers doing any volume have their own money full stop and are not going to look to others for funding of EM..

Then deposit EMD for transaction with property owner?

Also forces the seller to deal with the deposit reconciliation. 

No security deposit either. 

I think this would make sense in the long run for the rental property as it will extend the life of everything it touches like the Sink, faucets, showers, water heater, dishwasher, and Clothes washer while also providing clean drinking water in addition to the reverse osmosis drinking water system I already have installed.The main problem with this hardness level is that we get a major deposit buildup on all of these items, which will eventually clog up the faucets for tenants and lead to rusty shower enclosures that take forever to clean.In addition to this, it looks like we could likely have the salt added every couple of months by the property managers in addition to that it would allow for a quick inspection from them, and then also we would instead bill the cost of the service onto the ledger for the tenants.For reference, it does not look like the landlords in the area have water softeners.Thank you everyone for your input ahead of time.