Mike;

These are a good questions! I will probably publish it on the in The Spa Care Tips News letter.

Years ago and today on some obscure spas, they placed air channels set in the spa shell, under the seats and in the foot well. They drilled small holes out in the seats to let the air bubbles in the spa. These channels were quite large, and would grow bacteria, if the air blower wasn't used.

If the air blower is used regularly at least three times a week, there is no problem with bacteria (with proper sanitizer levels). You do not have to blow out every drop of water every time. The channel will be refreshed often enough. I have seen hundreds of these spa in use with no problems.

The only time there will be a problem with this type of blower, is if the spa blower isn't used. Then the water inside the channel is not refreshed often enough, and it can grow some microorganisms.

This is not the case today. With the advent of modern air injector jet systems with manifolds, we have small air channels that do not hold as much water, and the control systems on most upper level spas, will run the air blower automatically every day for enough time to clear out any water and put it back into circulation. Even so the amount of water is small, and when blown back into circulation is disinfected immediately as it mixes with the main water. There is also a one-way check valve that limits the amounts of water that can back into the air tubing.

Spa companies who do not have air blowers, often try scare tactics to sell the non-blower system.

It is particularly true on fully foamed spas. They do not operate efficiently with an air blower system. All they do is draw in cold air. On a true thermal lock or thermal pane insulated spa, the air is warmed automatically before being added to the water.

If you are trying to save manufacturing money, trying to keep the cost down of operating a poorly designed spa, and keeping the profits up, you will make a fully foamed spa, which naturally wastes energy.

You probably should not even have air controls for the jets on a fully foamed spa, because they also draw in cold air.

If the entire cabinet is full of foam, where does the air come from that is drawn into the water?

In some spas with two water pumps, the water in the second pump, is much more prone to stagnation, if the second pump isn't run at least once a day. There is about ten times the amount of stagnant water in a second jet pump system than in a modern manifold air blower system. Can you imagine paying $8000.00 for a spa with no clean-out cycles on the second pump?!! It happens every day. Some of the most popular (and well hyped) tubs today use a simple cheap control system with no automatic second pump clean out. They also have no blower, a tiny worthless "circ" pump that makes the first jet pump water stagnant also.

I hope they will change their designs soon!

If the spa sets for a week without anyone using the second pump, it is worse than any air blower. This can be solved by simply running the pump for at least 20 seconds three times a week.

On some old fashioned spas, with the outdated tiny "circ" pump there is a big problem of stagnant water in the jet pump plumbing, if it is not run every day. This is only one of many reasons why the tiny circ pump is worthless.

The best filtration system:

The best filtration system, uses a total filter fiber from 25 square feet to 50 square feet (100 Sq. Ft on some high volume pumps), runs a pump with at least 40 (GPM) Gallons per minute for 4 to 12 hours per day in two separate intervals. It runs the second jet pump for 20 to 30 seconds every day as well as the air injector system for 20 to 30 seconds every day.

If you are forced to run the filter pump for more than 12 hours per day and there is more than 100 square feet total filter fiber, something is seriously wrong with the design.

In the best filter system,the filter is not completely plugging the suction of the pump, so that all the water is not forced to go through the filter(s). If so plugged, the jet pressure drops as the filter(s) becomes clogged, giving less and less therapy until the filters are cleaned. This makes for more frequent maintenance and poorer filtration. A newly cleaned filter is not as effective at removing smaller particles. This (type of 100% filtration) makes the pump work harder and draw more amperage (more electric costs), while at the same time it runs hotter as the filter(s) becomes more plugged because it is working too hard. It also cost more in filter replacements, because of multiple filters and using more than 100 square feet of filter fiber. Because this poorly designed type of 100% filtration is not drawing any water from the bottom of the spa, the water in the foot-well is not circulated and filtered enough. With this poor design all of the water is brought to the pump from the filters which are only getting water from the top of the spa. I have seen these filters with the sides caved in from being clogged and having no relief for the suction. When any one touts "all of the water all of the time", this is bad!

On a good suction side filter system (or pressure), there is a safety suction plumbing fitting at the bottom of the spa taking a partial flow from the bottom, this insures that the water in the foot well is circulated. As the filter gets clogged with use, more water is naturally drawn in from the second suction. In this way the pump is not forced to work so hard, and the jet pressure stays much higher as the filter is doing is normal job. You do not need a shut down switch if the suctions are installed correctly. There is no possible way to become caught on a standard NSPI designed suction system.

Because the water is circulated well with a modern high volume two speed pump there are no stagnant areas in the vessel as with the tiny "circ" pump models. Tiny "circ" pumps do not move the water much at all, thus they need some serious help from the main jet pumps. You will find that these spas have extended run times on the main pumps to clean the water.

The ratio of gallons of water per square inch of skin in a spa is great, requiring a much higher rate of water change over than in a swimming pool.

Any spa of 500 gallons or less with more than 100 square feet of filter fiber, has serious design flaws in the filtration system.

These systems only work inexpensively in a spa with out full foam, using full thermal lock that captures the waste heat from the motors, and transfers that energy back into the spa water! It actually costs less to operate a 40 GPM pump twice a day for eight hours total in a thermal lock spa, than to run any other spa filter pump system.
I wrote at length about these subjects in my booklet "How Spas are Made".

So if you want full jet pressure, clean water, low operating costs, and enjoy your spa more, you need a spa designed as I described.

I hope this answers your questions.

Please write again. I am sure there are some questions that have popped in your head as you read this letter!

Thanks:

Jim Arjuna
The Spa Specialist Inc.
555 Alter St. #19A
Broomfield, CO 80020
(303) 404-AAAH!