We have a customer that uses well water for mixing the field marking paint. Here's his question,
"One question, we dilute our current latex paint with well water (i.e. hard water). We have had some issues with the quality of the lines. Is there any additive we can use to soften the water we are using that would help the paint and water mix a little better?"

Here are a couple suggestions you might try.

We've heard people us Downey fabric softner in the paint mixture. I have not personally tried this. I doubt that this would hurt the grass at say 1-2 ounces per 5-gallons of diluted paint mixture. One thing with using a soap like mixture is it acts like a surfactant and will help with
the bonding affect on the grass. Unfortunately this may have an adverse side affect of producing foam which pumps do not like. If you are using a return line then this may cause problems. I would add this as the last step in your paint mixing (after adding the water which should be poured into the mixing container versus using a hose and exposing the water stream to air).

I will use a little dishwasher soap in my weed killer (2-4-D) application to get a better bonding affect.

There is a flow-conditioner product for acrylic latex paint that may help called "Flotrol". The product is sold to provide a smoother paint texture during application. It can be found in most paint and hardware stores. I've found no foaming problems with this product in our Model E-100 field marker.

Another product that I use to help clean the pumps during the final rinse cycle is "pump protector". It is another pump lubricator and acts as means to keep any residual paint in suspension when left in the system. I've had no problems mixing this with paint (or in the next mix batch of water) and no side affects on the grass. There are two different manufacturers of this type product and you find it in most paint and hardware stores. I've found no foaming problems with this product

I would first try Downey, then the pump protector product to see if that improves your paint mixing performance.

Often times the quality of the paint will have a direct impact, the more finely ground solids in the paint will produce better quality mixing operation.