Starting TFP method for my spa for the first time

[sivart]

A couple of months ago, I switched over to the TFP method for my swimming pool, and that has gone very well so far. With that behind me, I've decided to try the same with my hot tub. I've got a 2011 Hot Springs Sovereign with a Nature2 cartridge (changed every 6 months) and an ozonator, and the spa company I purchased from had me on this regimen: fill tub, shock with spa guard enhanced spa shock, add Silk Balance. Once a week, 1.5 caps of spa guard enhanced shock and 3oz of Silk Balance. That's it! Actually, this seemed to work pretty well for a few years. After that, the black stuff started growing around the controls and all over the pillows. I think my ozonator had died, and I didn't get it replaced for quite a while. The water never looked cloudy, but I'm sure it had all sorts of issues. I would like to straighten this thing out, and I have a few questions after reading the Nitro post and several other threads.

I just emptied and refilled the tub. I have tested the CH (125) and TA (95) while the water is still in the 70's and heating up. I'm going to use the acid / aeration method to lower the TA to around 50. I haven't tested the PH yet, because I believe I read that the PH test may vary by temp and that I should be testing the PH at the temp that my spa will be at normally. That is true correct?

I want to use the dichlor / chlorine method of raising CYA and ongoing sanitation. I have a large jug of Spa Guard Enhanced Shock that I need to use up. I assume that I can use this for the dichlor part of this method. The label says: 58.2% Sodium Dichloro-s-Triazinetrione 41.8% Other Ingredients. The other dichlor products I see being sold are over 99% Sodium Dichloro-s-Triazinetrione. Does this mean that the product I have has more CYA in it, or can I use the section at the bottom of Pool Math to determine how much CYA I'm adding by choosing dichlor and adding about double the amount of Spa Guard Enhanced Shock?

Thanks,
Travis

 

[Oly]

Hi Travis,

You should have properly cleaned the tub and all the plumbing before the final fill. Do a search for biofilm and hope you don't have any lurking below the water line.
Assuming your pool is a TFP then you have a quality test kit correct? You can monitor pH regardless of temperature and rather than stressing about your TA just keep pH in the range with small doses of MA. Monitor you CYA with the test kit as you approach your calculated target and realize it falls in concentration much faster in a hot tub than a pool.

Now your Spa Guard is more than dichlor as stated on the label......Multi-purpose shock with four benefits in one: shock, clarifier, flocculent and pH buffer
Go buy a one pound bag of dichlor + CYA only and follow the Nitro post.

 

[sivart]

Thanks for the reply Oly. I've read about biofilm, and it is certainly a possibility that I have some. I bought the tub new so I know there wasn't anything lurking before I got it. The water has never been cloudy - always very clear, but that might not mean anything since I do have something black growing around the controls and on the pillows. I may decide to flush it out the next time around, but I decided to just refill and see if I can get things balanced as is. If there is biofilm, I've been sitting in it for a while now.

I do have the TF100 test kit. I was curious about the PH test, because of this previous thread saying that it was temperature dependent.
Effect of Temperature on Calcium Hardness Reading

Since my original post, I've been following the Nitro post trying to balance the PH. I've added acid to bring TA down step by step, but it isn't balancing as suggested. I've now added 5.2oz of MA, and the TA is down to about 35, and the PH is back over 7.8. So I'm not really sure what is going on there. I won't be adding any more acid at this point. I'll test again tomorrow.

I'll also buy a bag of dichlor tomorrow and avoid using the Spa Guard. I guess the tub should be fine overnight with no FC @ 100 degrees?

Thanks again

 

[Oly]

You are factually correct, the pH of a solution will decrease as the temperature rises although the acidity does not change. At room temperature, 77 degrees F. the pH of pure water is 7. If you increase the temperature to 212 degrees F, the pH of pure water is 6.14, which is still neutral on the pH scale even though it is lower than 7 The change is slight in the range we are dealing with and too small to be picked up by our basic testing methods.

How many gallons does your spa hold?

 

[sivart]

The spa holds 350 gallons. I just tested again this morning and got the following results:

PH 7.8
CH 125
TA 35

When I say TA of 35, I mean that the solution technically turns a dull pink after 3 drops and bright red after 4 drops. So the 4th drop does make a color change difference. Is that the correct way to measure that sort of thing or should I be saying that the TA is at 30, because it is no longer green after 3 drops?

I guess I'll leave that alone for now and head up to the store for some dichlor + CYA.

 

[Oly]

Just to be clear the dichlor has CYA so no need to buy any CYA adding the dichlor will be adding chlorine and CYA. Use pool math to estimate total need to bring your CYA up to 30 but do not add all at once rather just in small amounts with the goal to keep your FC in the target zone, then get in and enjoy your tub. Keep records of your dichlor additions and when close to estimated total needed, confirm your CYA with your test kit then when at 30 switch to liquid chlorine. Check your CYA every 2 weeks going forward to watch for a decline in CYA and switch back to dichlor to bring CYA back to 30 if it drops. Over time you will learn your system and can check less often.

Don't stress the TA target just keep your pH below 7.8+ with acid additions. If your pH rapidly changes radically up or down then you can focus on your TA. Test your fill water for TA.
Anticipate sanitation needs when the tub gets a lot of use and test for FC and pH every time you're in.

 

[sivart]

Thanks for the assistance Oly. I'm familiar with using Pool Math at this point so I think I'll be good from here. The calculator specified that I should add 5tsp of dichlor to get the spa to an FC of 10ppm. I did that and tested about 30 minutes later and the FC was at 5ppm. Pool Math says to add 2tsp dichlor to get from an FC of 5ppm to 10ppm so I added another 2tsp, and it tested at 10.5ppm about 20 minutes later. So I guess there was something that needed to be burned off from the fill water / overnight sit with no FC. Based on the calculator, I'm estimating my CYA to be at almost 14ppm now. I'll bring it up to about 30 and take it from there. I'll post if I have any further questions, and thanks again!

 

[Oly]

Sounds good sivart enjoy your spa.
Another difference with a spa is the combined chlorine level can stay higher than your pool and it does not go down as easily due to being covered, so keep an eye on this especially after a couple months of regular usage. High CC from slow to oxidize organics can be a serious skin irritant and put a real damper on a relaxing soak.
I have been able to reduce the CC by raising the FC then opening the cover during the day and running the jets but eventually the spa will need to be drained and cleaned for best results, fortunately this is an easy process with a small stand alone spa system.
How long you can go depends upon your spa size and how much it is used.
A Water Replacement Interval (WRI) used by the spa industry which in person-hours is (1/9) x (Spa Size in Gallons) / (Person-Hours Per Day). Some say using the dichlor / bleach method this interval can be doubled which is my experience as well. You may want to read this article but I will warn you it may be too much information but it does drive home the importance of draining your spa periodically .....Spa Soup: Why We Dump Spa Water - AQUA Magazine

 

[sivart]

I bought the spa new in 2011 so I've had it for quite a while now, and it is actually my second Hot Springs spa. I have been doing a drain and refill every 6 months, and it is always much more enjoyable for the first month or two after a refill. I expect things will be better with this method. Previously after a few months, the bubbles that would rise to the surface (especially during windy conditions) would pop and sting the eyes. I expect this was from the terrible PH condition of the water. I feel like I'm on my way to a much better experience.

On another note, I'm hoping that the black growth around the controls will go away. The dealer I bought the spa from called this black algae, but I don't think it is algae. Isn't this mold? I have no idea, but it is very persistent. I'm hoping that the off-gassing will get rid of it. It is all over the soft pillows, and those may not recover. I've got new ones, but I won't put them in until the rest of it disappears for a while.

 

[karendino]

I used the Nitro method and my HT has been outstanding. I did not use Dichlor to raise CYA. I had some stabilizer so used it and went straight to bleach. My fill water was 110 so I did the TFP method of lowering TA to 50. CH fill water was 125, so that was good. Fill PH was 7.6.

The HT has been balance so well. I only had to add CYA once in 2 months, and one time had to add MA. I m impressed with Nitro's method.

 

[sivart]

I'm only 4 days in, but I can already tell the HT is in much better shape. The water is sparkling, it has that nice clean smell, and the black stuff around the controls is fading away. The pillows may be a lost cause (I'll let them sit in the water the next time I shock it), but I've got new ones to put in once I'm sure the black menace is gone. The boric acid I ordered from Duda just arrived so I'll be adding that next. I want to try it out in the HT before deciding on whether or not to add it to the pool.