Tuesday, February 17, 2009
Spa 2 Go - Filter Maintance - 4 of 7
Maintenance is the key to keeping your Spa 2 Go healthy and working. There are only two primary components of maintenance: Filter and water chemistry.
Let's talk about filters. The S2G uses a special filter, it is primarily composed of a pleated paper filter element with a foam filter ring. Because of this special feature the filter is not universal. Instead special filters need to be purchased from S2G or its distributors, at a cost of approximately $50 for two. If you are a new S2G owner, buy a set. The filter pictured to the left is NOT the one you want. Instead you need the two stage filter pictured to the right. The proper orientation of the filter is as shown, foam ring down. This is a very crucial aspect of the filter and I will explain later.
Set a filter replacement schedule. Two weeks is ideal, a month at the maximum. Follow the instructions that came with your hot tub. The filter fits within a protrusion, both in the filter tank and one the filter cap. Make sure it is seated before attempting to screw down the lid. If not you can crack the filter foam clip ring. With a new filter in place, the old filter can now be cleaned. I usually use a handled shower head for the cleaning. Be careful of using too strong a sprayer that might tear the paper element. The paper element is fairly tough material and can withstand many washings. You just need more than one filter so that you can swap out the current filter. Do not run the spa without a filter. It is very easy to jam the impeller with debris.
Most filters should be cleaned from the inside out, or back flowing. This filter however is difficult to do so, due to the small inner orifice. I however will still start from the inside, then move to spraying down and dislodging material from in between the pleats. I always finish off with a final spray from the inside out. Next comes the foam ring. Actually I unusually clean this off first. Be careful trying to remove the blue ring which clips to the filter body. Though it holds the foam ring in place, this blue clipped ring easily breaks. Try your best to clean the foam, but you will most likely find out that the foam just falls apart. If it does just throw away the foam. This is the reason why most people just buy new filters. Finally I fill a small bucket with water and put a dollop of bleach in it. Sink the filter and let it soak over night. Spray the filter off before allowing it to dry.
If you suspect the foam ring to be deteriorating at all discard it. Bits of the foam ring can easily become lodged in the pump and jam the impeller. Go to a fish tank supply store and purchase a sheet of generic filter foam, pictured to the right. A sheet can be had for less than $10. The picture above shows the "stock" filter and foam ring at the left, and homemade foam section in the center. The replacement foam ring is quite dirty in the picture. Take the fish tank filter and cut a strip of foam material, and Viola, new foam filter!!
With three filters you can rotate between them, and always have a clean filter ready to go. Final, a note of caution. After a filter change, it is easy to forget to turn the system back on. If you live in sub zero climates, this could be very bad for your tub. Also when the system is shut down it resets itself of 100 degrees. This is usually a tad cool for most, and you might go a few dips before you realize that it is at its default temp setting.
This next section is extra credit reading on why S2G changed there filter design and it has to deal with pump cavitation. Now if you are into pump tech, you might disagree with some of the following details. I did not go back and reread chapters in my Fluid Mech book before I wrote this. How ever the logic is basically sound.
To put it in a nut shell, the old filter design provided too much flow resistance for the pump. So a foam ring was added to insure that enough water reached the impellers of the pump unit. Since the suction is located at the center bottom of the inner filter tube, the foam, needs to be at the bottom so that the water can reach the pump.
The term used is available head. Which is the available amount of pumping medium for the pump to draw from. I forget why the term "head" is used, but I always think of, head of foam on my beer, as an indicator to the available amount of beer there is in the glass. The resistance of the paper element, might have increased due to the washing. The paper membrane could become clogged and flow less, then when it was new. However it is common practice to wash spa filters, and thus suggest that there was a design flaw, which S2G corrected by a new filter. Without the proper available head, the pump can and does cavitate. Cavitation is commonly thought of as a water pump, pumping air. I have heard the term incorrectly used to describe a boat propeller when it comes out of the water and spins in the air. A pump impeller however can cavitate even if it is submerged in water but does not have the available amount of head. The reduction of pressure, or vacuum created by the pump can actually draw gases out of solution. If you fill a syringe halfway full of water, plug the end, and pull back hard on the plunger, you will see gas bubbles appear in the tube. Same thing happens on the leading edge of a pump impeller. These gas bubbles form violently and can cause pitting and damage to the impeller blade. But the real damage cavitation does is the vibrations. It destroys the pivot that the bushing or bearing that the impeller shaft rotates about. The S2G pump can cavitate if the filter tank is not bleed properly, or if the filter is installed with the foam ring towards the top, and the pump is not supplied with the nessary amount of head.