How do I inform customers the necessity of increasing prices for a swimming pool and spa service

There's no good way to do this, but there are plenty of bad ways.

(But first... is it possible to keep your existing customers on whatever service level they're at and only increasing your service for new customers?)

One bad way to avoid is to simply blame your higher costs. About a year ago, a service I had sent a letter saying that next month, the rate was going up because their costs of doing business have increased. No kidding. Whose hasn't? I no longer use their service.

I think the best way to notify your customers is to:
1) start a letter (or email or whatever communication you use) reminding your customers of what great service you provide - remind them why they use your service - why you're the best
2) if possible, personalize it - "Customer Smith, You've been a great customer for X years. Thank you!"
3) Add an incentive to stick with you... "Our rates are going up as of Jan 2008, but if you contract for X months now, we'll give you X percent off"

As a consumer, I would certainly appreciate a business that's trying to keep me as a customer rather than one who's just passing on their sob story.

Hope this helps!

-Adeena
Author of "Cute Little Store: Between the entrepreneurial dream and business reality"

Accuarate answer but I want more lines that helps me for writing a letter to my customer.