Lost the valve cap for the water tank

try pouring a little vinergar in the water and let it clean and only use distilled water in the humidifier otherwise the impurities will stop it up

The valve on the bottom of the tank is either too tightly twisted on or needs cleaning. Be sure when you push up on the little plastic piece that sticks out that the water comes out quickly (do over sink). If not, loosen the filling cap, clean the valve and screw cap back on, but not too tight.

Have you cleaned the unit lately? The following is from the owners manual.
1. Turn the humidifier ‘OFF’ and unplug the unit.
2. Lift the main housing and remove the water dispersion tray and the PermaWick™ Filters. The motor is attached to the main housing. Do not place the motor near water. Do not use a wet towel on the motor or motor housing as electrical shock may occur.
3. The PermaWick™ Filter should be cleaned in a vinegar and water solution to remove any mineral buildup. Place in a solution of one (1) gallon of water and eight (8) ounces of undiluted white vinegar. Allow the filter to soak for 20 minutes.
4. After soaking, rinse it several times with clean water. Place the PermaWick™ Filter in a location where it can drip dry while you clean the other parts of your humidifier.
5. Remove the water tank from the base and empty any water that is left in the tank. Soak the base in a mixture of one (1) gallon of water and eight (8) ounces of vinegar for 20 minutes.
6. After soaking, wipe the base with a soft cloth or sponge to remove any mineral build up. Rinse with clean water several times. If you are planning on storing the humidifier, be sure the base is completely dry.
7. Fill the water tank with one (1) gallon of water and eight ounces of undiluted white vinegar. Replace the tank cap and shake the tank vigorously until all interior surfaces of the tank have been exposed to the water/vinegar mixture.
8. Empty the tank of the water/vinegar mixture. Rinse it several times with clean water and then replace the tank cap. If you are planning on storing the humidifier, dry it inside and out, leaving the cap off to allow the tank to completely dry. Continue to clean the other parts of your humidifier.
9. Remove the water diffuser cap by squeezing the two tabs as shown in Figure 3. Rinse the cap in clean water to remove any debris. If the cap contains hard water residue, soak it in a mixture of one (1) quart of water and two (2) ounces of vinegar for 20 minutes. 41553-01 01/03/2008 6 © 2008 Hunter Fan Company
Rinse well and reinstall the water diffuser cap. Do not expose motor or other electrical components to water.
10. Wipe the surfaces of the main housing with a soft cloth.
11. Once all the parts are clean, reassemble the humidifier, and follow the USING YOURHUMIDIFIERto continue use. If you are storing the humidifier, make sure the parts are completely dry, reassemble, and store in a dry location

The instruction manual suggests using the water vinegar solution.
The following is from the manual.
1. Turn the humidifier ‘OFF’ and unplug the unit.
2. Lift the main housing and remove the water dispersion tray and the PermaWick™ Filters. The motor is attached to the main housing. Do not place the motor near water. Do not use a wet towel on the motor or motor housing as electrical shock may occur.
3. The PermaWick™ Filter should be cleaned in a vinegar and water solution to remove any mineral buildup. Place in a solution of one (1) gallon of water and eight (8) ounces of undiluted white vinegar. Allow the filter to soak for 20 minutes.
4. After soaking, rinse it several times with clean water. Place the PermaWick™ Filter in a location where it can drip dry while you clean the other parts of your humidifier.
5. Remove the water tank from the base and empty any water that is left in the tank. Soak the base in a mixture of one (1) gallon of water and eight (8) ounces of vinegar for 20 minutes.
6. After soaking, wipe the base with a soft cloth or sponge to remove any mineral build up. Rinse with clean water several times. If you are planning on storing the humidifier, be sure the base is completely dry.
7. Fill the water tank with one (1) gallon of water and eight ounces of undiluted white vinegar. Replace the tank cap and shake the tank vigorously until all interior surfaces of the tank have been exposed to the water/vinegar mixture.
8. Empty the tank of the water/vinegar mixture. Rinse it several times with clean water and then replace the tank cap. If you are planning on storing the humidifier, dry it inside and out, leaving the cap off to allow the tank to completely dry. Continue to clean the other parts of your humidifier.
9. Remove the water diffuser cap by squeezing the two tabs as shown in Figure 3. Rinse the cap in clean water to remove any debris. If the cap contains hard water residue, soak it in a mixture of one (1) quart of water and two (2) ounces of vinegar for 20 minutes. 41553-01 01/03/2008 6 © 2008 Hunter Fan Company
Rinse well and reinstall the water diffuser cap. Do not expose motor or other electrical components to water.
10. Wipe the surfaces of the main housing with a soft cloth.
11. Once all the parts are clean, reassemble the humidifier, and follow the USING YOURHUMIDIFIERto continue use. If you are storing the humidifier, make sure the parts are completely dry, reassemble, and store in a dry location.

This is the link to your manual:
http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

CAUTION:
Always be sure that the appliance is unplugged and switched OFF before cleaning or attempting to store the item. NEVER PLUG OR UNPLUG UNIT WITH WET HANDS.
DO NOT leave water in water tank or water basin when unit is not in use as it may result in the build up of mineral deposits and bacteria that can inhibit the output efficiency of the humidifier.
PLEASE NOTE that if water remains in the water tank for more than a day or two, bacterial growth is possible.
ALWAYS use fresh cool water when using unit.
NOTE: When removing water tank, water may accumulate under vapor lid and on the bottom of the water tank. It is recommended to have a dry cloth ready to dry wet surfaces.
DISINFECTING THE WATER TANK AND WATER BASIN
1. Fill water tank with 1 teaspoon of household bleach in 1 gallon of water. Let stand twenty minutes, shaking vigorously with two hands every few minutes, drain and rinse with clean water until the bleach smell is gone. Dry with a clean cloth or paper towel.

2. Wipe the water basin with a soft cloth dampened in the bleach and water solution. Rinse the water basin with cool water to remove any bleach smell. DO NOT IMMERSE WATER BASIN IN WATER.

3. Wipe all exteriors surfaces of the base with a soft, dry cloth. Do not immerse the base in water or use water to clean the base. An electric shock may result or the humidifier may be damaged.
NOTE: It is recommended to clean humidifier with water and bleach solution as stated above after using the humidifier the fourth time.

GENERAL MAINTENANCE AND CLEANING
Before any cleaning operation, switch the humidifier off and unplug it.
1. Always unplug the unit before cleaning.

2. The humidifier must be drained and cleaned before storing.

3. Once unplugged the exterior of the unit may be cleaned by wiping with a soft dry cloth. Caution: The ON/OFF switch must be thoroughly dry before unit is again plugged into power source.

4. There may be some lime deposits in the nebulizer, particular in areas with hard water. Overcome this drawback by cleaning the nebulizer with water and vinegar on a soft cloth regularly, as follows:

A. Dampen a cloth with vinegar and wipe the nebulizer gently, until the lime deposits disappear completely.

B. Rub down gently with a dry cloth and remove remains of humidity.

C. Do not rub the nebulizer with solid objects.

D. Do not clean with chemical products

5. When cleaning the water basin do not place the nebulizer directly under the water tap.

6. Never immerse the unit in water or let water enter the fan vent (see figure 3) or any other openings.

7. It is normal for water to be in the water basin. However water must not get inside the central body. If this should happen, take the humidifier to an authorized service center before using it again.

8. Clean the inside of the water tank at least once a week, as follows:

A. Fill the tank with clean water adding a few drops of bleach. Close the tank completely with its cap and shake by holding the tank with both hands. Do not hold by handle while shaking the tank.

B. Rinse thoroughly.
Water Level Sensor- The water level sensor is made of three key parts. When cleaning DO NOT MISPLACE these parts and MAKE SURE that you assemble these three parts correctly after cleaning and before operating humidifier. They are as follows:
Plastic Cap – this part has 4 flat tabs coming out from the bottom and is placed on top of a plastic pin.
Water Float - a small round part resembling a "life saver" candy located underneath the plastic cap.
Pin – plastic pin that secures water float and plastic cap.
To clean the water float unscrew the plastic cap from the pin. Remove the water float and clean by wiping the parts with a soft damp cloth. Replace the parts by first putting the water float onto the pin and re-screwing the plastic cap onto pin.



Good Luck.

As the previous poster said, it's probably a problem with your water.

Are you using tap water or bottled mineral water? If so, there are minerals which get nebulized along with the water, and leaves a white, dusty, residue. I fill my Crane Pig humidifier with DISTILLED water, which is pretty pure. Make sure that the water is DISTILLED ONLY, since some of the water companies distill the water and then add minerals back in (they almost got me here until I noticed the label that said "with minerals added"). The reason this is important is because during the distilling process, the water is boiled, evaporated, and then the vapor is condensed back to liquid. This removes any impurities or dissolved minerals from the water. You can see Wikipedia for more on this topic here.

Additionally, I use both the Crane Demineralization Filter Cartridge (which works for the penguin as well, and gets installed in place of the original water tank cap), and the ProTec PC-1 Humidifier Tank Cleaning Cartridge (which I plop into the water tank) to keep the water both de-mineralized and bacteria free. I got both products at Amazon.com.

With these 3 things, so far I haven't had any white dust residue, and the mist feels fresh and clean.

On a side note, by using distilled water, you also prevent any mineralization from building up on the nebulizer or water level sensor, which can cause the humidifier to eventually stop producing mist...

sounds like new caps should solve it, but have you tried soaking the old caps in vinegar overnight? these guys are not the only ones, but they have the correct caps in stock at a pretty good price http://www.marbeck.com/humidifier_parts_bemis.html hope this helps :)