My well water was measured a few years ago at 11 grains. I've heard recommend to use STPP on a 1:3 ratio -- 1 part STPP to 3 parts detergent -- which is what I've been doing for a couple years. That may be stronger than necessary. A fellow I know who runs a hospital laundry claims he gets by with 1 *teaspoon* (or maybe I misunderstood and it's 1 tablespoon?) for a 50 lb load (not sure if that's on presoftened water). I've cut back to 1 tablespoon maximum the last couple months, haven't noticed any adverse effect thus far.

Do you need to add the STPP to powdered detergent only, or can you use it with liquid as well? If so, would you put it in the dispenser with the liquid detergent or into the drum with the clothes at the beginning of the cycle?

Since STTP is a pretty safe chemical and is non-reactive, I would say just dump it in your dispenser along with the liquid detergent. In your Bosch, I would reduce the STTP to 1 tsp. A little goes a very long way!

A possible concern regards to mixing powdered STPP with liquid detergent in a dispenser is that it can turn into a sticky mess that's difficult to flush through.

sshrivastava, welcome back!

"STPP will cause the fats in soap-style detergents to separate and float to the top."

HHhmmmmm...are there really laundry products that are mostly pure soap? Wouldn't the synthetic detergents and solubilizers ('hydrotropes') prevent that from happening?

I wonder if you need the stoichiometric quantity of STPP to complex ALL of the hardness ions (Ca++ and Mg++, mostly) or if a lower amount almost serves in some almost sorta...catalytic role of improving detergent efficiency without full complexation?

Sorry to be the Debbie Downer but I think people should remember - they (phosphates) can have negative environment effects and we should be mindful of that. Waste plant effluent is monitored for phosphate levels. If it keeps creeping up because of widespread use of 'aftermarket' STPP, well...legislatures gotta legislate! To wit: I hardly drink much alcohol but do peruse liquor stores once in a while...I have bought GEM clear to make botanical extractions from the garden...and I do occasionally enjoy the odd rarefied aperitif like Zirbenz...distilled from the finest swiss pine nuts! Anyhow, it cracked me up that after the ever-helpful Maryland state legislature passed a boneheaded ban on 190 proof alcohol, after some rich kid died from drinking, I dunno, punch he well-knew was spiked while at a frat party or something equally banal...distillers responded by creating Maryland-only 187 proof versions of GEM clear/Everclear/etc! It's the work of a moment to convert back to 190 proof OR HIGHER if you know what you are doing LOL. So, so, silly.

I have always added a bit of ammonia water to my laundry as a booster, and will now be adding some sodium borate as well. Have TSPP in the house but have only used it for laundry that is in desperate need of it, like the time I accidentally got used Kubota hydraulic fluid all over a pair of jeans. (it got it out) Granted I don't have hard water...for those that do, I can appreciate there are probably advantages to using it in every load.