Q - Are there any low-electricity usage devices to reduce the amount of chemicals that I need to purify my swimming pool water? The chemicals are expensive and they irritate my eyes. D.C.

A - The lowest-electricity-usage types of swimming pool purification devices use the ionization principal to kill algae, bacteria, etc. Using an ionization purifier can reduce the amount of standard chemicals needed by up to 90 percent.One new type of small (about 1 foot in diameter) ionization purifier floats on the swimming pool water and is powered by free solar energy. Solar cells are built into its top. They provide the small amount of electric charge needed to produce the silver and copper ions.

It takes several weeks for the solar-powered ionizer to build up the silver and copper ion levels to the point of adequate purification. Once the water is at the proper ion level, only small additional amounts of ion generation are needed. It then requires just several days use per week.

The purifying ions are not quickly lost from the water due to heat and evaporation like standard pool chemicals. Replacement ion electrodes, which last several years depending on pool usage, cost about $40.

House-current electric-powered ionization devices cost only about $5 to $10 per year for the electricity to operate them. The water is exposed to only very low voltage. The replacement electrodes cost about $100 per set.

In this type of system, the ionization chamber and electrical controls are located outside of your pool, often near the filter pump. The existing water filtration pump circulates the water through the ionization chamber.

You use a water test kit to measure the level of copper ions in the water. The concentration of silver ions is much lower than for the copper. There is an adjustment dial on the electronic controls that allow you to maintain the desired ion concentration level.

Even though you maintain the proper ion concentration level, you still have to use some standard purification and pH-level chemicals. A periodic "shock treatment" is needed if the water gets cloudy after very heavy usage, a rain storm, etc.

You can write to me for UTILITY BILLS UPDATE No. 399 showing a list of manufacturers and product information on the solar-powered and standard electric-powered ionization swimming pool purification systems. Write to James Dulley, The Deseret News, 6906 Royal Green Dr., Cincinnati, OH 45244. Please include $1.00 and a self-addressed STAMPED BUSINESS-SIZE envelope.

Q - I have made my house more airtight to save energy and my allergies seem to bother me more now. What exactly are dust mites and what can I do to control them? K. Y.

A - Dust mites are very small animals, about the size of a grain of sand, that live in your bed, carpets and furniture. Many thousands of these survive by eating tiny flakes of dead skin that drop off our bodies.

They stay pretty well anchored, but their tiny feces pellets and worn out shells become airborne when you walk on the carpet, shake out the bedding and vacuum. These get on your mucous membranes and cause allergies.

The best way to control them is to keep the relative humidity lower. The mites don't survive well below 50 percent relative humidity. A high-quality air cleaner can also help to remove some of the airborne particles.