Matthew Thompson

What is the buildup inside my Bosch dishwasher?

My Bosch SHU5315UC-12 has buildup inside - it doesn't appear to be black or mold, but it is kind of tannish and mushy in texture. We did a thorough cleaning of the dishwasher (or so we thought) a few months ago but noticed it's coming back. Now, we've taken apart a lot of the parts that route and spray water inside the wash compartment and are discovering this stuff everywhere. We think we've gotten rid of most - if not all - of it. What's the deal? Why is this happening? Any suggestions?

Dishwashers , Appliances
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2 Answers from these members:
Manage My Life
Inappropriate amount of dishwasher detergent for

the degree of water hardness or the amount of food


• The general recommendation is one teaspoon of detergent

for each grain of water hardness (gpg), with a minimum

of three teaspoons when water is soft.

Refer to the following chart:

Water Hardness Detergent Use

Soft (0-3 grains) 3 tsp.

Medium (4-9 grains) 4-9 tsp.

Hard (10-13 grains) 10-12 tsp.

Very Hard (14G grains)

To determine water hardness:

a. Use a Water Hardness Test Kit

(Maytag Part No.038184).

b. Contact the local water utility or state university

extension service.

• For normal or longer cycles, place the prescribed

amount of detergent in each of the cups.

• When choosing a light wash or shorter cycle, place the

prescribed amount of detergent in the main wash cup


3. Improper loading.

• All items should be loaded so they are separated and

facing the center.

• Large bowls or pans should not be placed over the center

of the lower rack where they could block the wash

action of the center spray tower.

• Larger items should not be placed so that they shield

smaller items from the wash action.

• Bowls should not be nested together as water is then

unable to reach all of the surfaces.

• Spoons and other silverware should be loaded with

some handles up and some down to prevent nesting.

• Avoid loading items in a manner that would restrict the

rotation of the spray arms.

• Avoid loading large objects in a position that would

block the detergent dispenser from opening.

4. Improper water fill.

If the water level is low:

• Check to be sure that there are not other hot water

activities (such as laundering or showers) occurring at

the same time the dishwasher is running.

• Check that the dishwasher is level from front to back

and side to side.

• Check for an immobilized float.

• Check for low water pressure.

5. Use of old or caked dishwasher detergent.

• Detergent should be fresh and stored in a cool, dry


• Detergents should NOT be stored under the kitchen


• Detergents should not be stored for extended periods of

time prior to useUse of too much dishwasher detergent (especially

liquids and gels) for individual water conditions.

Iron or manganese in the water supply can cause

brown, red or black stains on dishes or the dishwasher


• To remove this type of discoloration on dishware and

the dishwasher tub, use a rust remover such as RoVer*

Rust Remover (Part No. 057961). Do Not use RoVer

with metal items.

To Use:

a. Fill both detergent cups with RoVer.

b. Set the controls and run a normal wash cycle.

c. Follow with an additional rinse cycle.

d. DO NOT use RoVer with dishwashing detergent.

A lime film or deposit may eventually build up on the

dishwasher interior if there is a high calcium level in

the water supply.

• Try ONE of the following procedures to remove this

type of deposit:

a. Use a damp cloth and a mild scouring powder.

b. Initiate the Rinse & Hold portion of a cycle (with an

empty dishwasher). During the fill, open the door

and add 1/2 cup white vinegar to the water. Allow the

cycle to complete (without detergent). Follow with a

Normal cycle with detergent.

c. Fill both detergent cups with RoVer* Rust Remover

(Part No. 057961). Set the controls to complete the

Normal wash and rinse cycles. Follow with a shorter

wash cycle with detergent. Do not use RoVer in the

cycle with dishwasher detergent.

Dishwasher Odor


1. Dishes washed too infrequently.

• Run a Rinse & Hold cycle, if dishes are being held until

there is a full load, to prevent food soils from causing

an odor.
by Manage My Life
August 18th, 2010
Answered in 15 hours
0 votes
Matthew Thompson
By the way, we've used Dishwasher Magic on the dishwasher - will keep on using, but that didn't seem to fix the problem.
by Matthew Thompson
August 17th, 2010
Answered in 46 seconds
0 votes
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