Water Change Formula and Question

[CalicoskiesNC]

The formula (from Dr. Spa): take the spa's gallons and divide by 1/3. Use that answer and divide by the number of people using the spa everyday.

Example for my Optima: 500 gallons.  There are 4 people on average using the spa everyday.

500 divided by 1/3 = 166.66 gallons
166.66 divided by 4 = 41.67 days

If you use your spa maybe every other day, your water may last longer. However, remember this formula is only an estimate and is used only to give you an idea. You may have special circumstances or unforeseen situations that may require you to drain your spa's water sooner. You must also remember that you will need to have the water chemistry well balanced for the longest lasting spa water possible.

So we have been going about 50 days before a drain but at around 45 days we will notice the drop from crystal clear to hazy and if air is used we get foam.  The water stays balanced this whole time.  We all shower before entry and  rinse suits and keep water balanced so that is not an issue.  So according to the general formula we should be making it to around  42 days which is right where we are at.  I was hoping to be able to make it closer to the three month mark but because I have five in the family and we still use it almost everyday for two or three hours total I guess I am doing ok.  That is the question by the way, am I doing ok or should I be getting more time with my water?  Thanks and I hope the formula helps others.  Joe.

[spahappy]

On the average I change water every 3 to 4 months. We have five in the family and our Coleman Spa gets used almost every day, most days by several different bunches of soakers.
I have short spikey hair which requires almost industrial strengh hair gel and spray to maintain. I never shower before using my tub. If my water starts to get cloudy I'll increase filtration and use a first filter on top of the skimmer basket for a few days, and shock a bit more often.
I believe that a spas filtration system along with a good chemical regimine is what will determine how long your water will stay clear.

Spahappy

[wmccall]

Your probably doing ok,  Because of this forum your probably noticing things with a more critical eye.  Most people don't notice the slight degredation in the water until they change it for the first time.   Want more time from your water?, take out 50-100 gallons, clean the filters and refill the water to its full level.

[Brewman]

I try to stick to a 90 day schedule, except for that winter hurdle, where it a closer to 120 days.  Water is always clear when we switch, or has been so far.
Brewman

[tony]

To date I have always drained and filled on a four month basis.  I also use swirl away, towel dry and apply spa gloss, change N2 and micro filter and do a general maintenance.  My water is always clear at four months, but I marvel at how nice fresh water is.  Now, after watching my CYA levels get up over 100, I am considering doing a quick water change half way between my regular full maintenance water change (except mid winter).  I am less concerned about TDS, but as water ages, it certainly gets a little harder to keep.

[CalicoskiesNC]

I'm keeping my ALK at 130, should it be 100?  It only costs me about $3 to fill my tub so I would just refill rather do the half change thing.  I do use the Swirlaway before draining, we spa gloss before each refill, and I use Metal Gon on the refill.  We clean our filter weekly with hose, monthly with spray cleaner.  

My dealer has no test for TDS or CYA, so I dont know what that number is when I notice my water "turn."  

Its ok if 50-55 days is all I can get out of my water based on the user load, but just want to make sure I am not the cause.