Pretend that it is printed -- and purchase an advertisement on LinkedIn. Search and find the perfect people and invite them to carry your product.
If you have to do a printed magazine your best bet will be the industry magazines which I assume since it is your market you would already know:
- Water Conditioning & Purification Magazine (www.wcponline.com)
- Water Technology Online (http://www.watertechonline.com/)
Both have classified sections.
Be sure that you are posted the ad on your own marketing site and through your own networks. Ask for referrals.
Recruiting resellers or reps is selling a business opportunity. It is a B2B sales campaign. It needs to be organized and supported as such.
Have you tried linkedin groups? thefunded.com ? Usually anyone interested will contact you.