FAS DPD really necessary?

[mrjetson707]

new pool owner here. I was speaking with my wife about the test kits and she said "it doesn't have to be perfect, you're thinking too hard about all this" referring to getting the pool balanced. I didn't really think about that. I understand the test strips aren't very accurate but they are cheap and does it really matter if your pool isn't PERFECTLY balanced? I know alot of you guys are very adamant about having your pool perfectly balanced so can you guys explain why it matters to have it dialed in to an exact point vs a ballpark range with test strips. I'm easily convinced it should be perfectly balanced so I need some ammo to convince my wife

 

[mknauss]

Test strips are rarely even close. And once you open the package, they are being contaminated.

How much did you spend on your pool? How much are you going to spend in maintenance and utilities each year on your pool? How much does it cost each year amortizing the plaster, pump, etc? A $100 test kit that will last pretty much two years is the least cost and most important expense you will have to maintain your pool.

 

[mrjetson707]

Test strips are rarely even close. And once you open the package, they are being contaminated.

How much did you spend on your pool? How much are you going to spend in maintenance and utilities each year on your pool? How much does it cost each year amortizing the plaster, pump, etc? A $100 test kit that will last pretty much two years is the least cost and most important expense you will have to maintain your pool.

how would you compare test strips to the accuracy of leslies pool free tests? I've heard leslies can be very wrong

 

[HermanTX]

I give you a recent example. I had to go purchase a weir door for my skimmer so I went to 2 pool stores. I took a pool sample to both (the sample was taken at the same time from my pool). The difference between the 2 stores were as follows - for FC it was 3ppm, for CYA it was 40 ppm, for CH it was 140ppm. How can the same tests be so far apart in results using the same water sample? (Also, the pool stores were only 15 mins away from each other) Now these are stores that are using test apparatus however they are operated by inexperienced personnel, no known calibration info and probably contaminated from the previous pool test. So if you go to test strips, you will be tempted to go to pool store as well for their "free" test - however - you really will not know if your pool "balance" is even close. Test strips give broad ranges that are even worst then what I received at the pool store.
BTW - my own testing is much more consistent.
For a $100 investment of a proper test kit for a pool that will probably be well north of $50,000 you will have confidence in knowing that you are taking care of your investment to the best of your ability.
Good Luck.

EDIT - Leslie's was one of my "free" pool tests I visited.

 

[TexEdmond]

does it really matter if your pool isn't PERFECTLY balanced

My pool has never been perfectly balanced, and it likely never will be. That's not the point here. The point is I've followed these steps and my pool is so much clearer and safer to swim in, beyond my wildest dreams... And it takes so little effort! It's a great big bucket of water outside and it's always changing and never quite "where it could be".

Early on it was a big realization: It's not necessary to check all of those levels every single day, so testing really isn't that big a deal day-in day-out.

As I started to get my pool aligned with TFP methods I also found that the strips changed colors that weren't actually on the charts. I don't know if it was because of our FC recommended levels or what. They just seemed to go haywire on me.

There's also an important lesson here around the difference between precision and accuracy.

These test kits we are so adamant about using have quite a bit of margin for error. It's the ability to have consistent, controlled, repeating results that we back up with a tested and proven calculator that gives us amazing results with often very little effort. For example: My pH comparator block has a resolution of 0.3. The calcium hardness and TA tests many of us use is a 25ppm and 10ppm per drop test, respectively. At recommended levels that's easily +/- 5% to 15% error per drop. Not exactly guaranteed accurate, but over time the results become very precise and repeatable, especially when we can take a measurement, dose a chemical, then measure again to verify.

Same with dosing any number of chemicals, and I've definitely fallen into the perfectionist trap there. For those of us with medium to large pools, the margin for error is incredibly forgiving. If I need to drop the pH by 0.2 (which my comparator block will not measure) in my 25,500 gallon pool, that's 11oz of muriatic acid. If I accidentally poured 20, I might fall just over 0.3, but I'll never be able to notice that small a color difference. It'll bounce right back, and if it doesn't, there's plenty of time to find some chem to bring it back.

Chlorine is even more forgiving. There's basically no downside besides slightly higher cost to dosing all the way up to SLAM levels with chlorine. This gets directly to your question in the subject line. The DPD powder test gives us either 0.2 or 0.5 (depending on test kit) resolution for FC and CC up to very high levels. There's tons of margin built into that CC test. I often see a slight color change for CC and log 0.5ppm CC when I know for sure it's probably 0.1 or 0.2. The important thing is, it doesn't take me TWO drops to clear the sample. That'd mean I had a serious problem, and that kind of direct measurement helps us determine when to start or stop slamming an algae bloom.

Then there's the CYA test. We round up to the nearest 10. No need for really any accuracy at all, no deep thoughts, just glance, record, retest if needed. Keep an eye on it over time and make sure it doesn't go too high. This is critical for us to set the groundwork for our baseline chlorine levels so we're not creating a dangerous pool on either side of the scale by having too much or too little free chlorine. But it's definitely not exact.

I think honestly both you and your wife are absolutely right. She's right when she says, "It doesn't have to be perfect. You're overthinking this." I did that for months.

And you're right too. Who wouldn't want to show up and "do it right" and take pride in their pool? Maybe see if she's okay with taking some photos of your pool now, and then again after 6 weeks or so of really giving it a go with our method. I don't know about y'all, but I definitely know I've blown $100 on something dumb and glugged it into my pool. What's the difference in buying a real test kit? If saving a fortune on flim-flam pool store fixes wasn't enough, would you pay $70-100 for a chance to have the respect and admiration of your spouse by telling her she was right, that it actually didn't have to be perfect but it still could be this good (and easy)?

And if you decide not to continue with testing like we do, I'm sure someone will gladly offer you a fair amount for your unused test reagents. There's test strips aplenty out there and we all know where to find them... We just choose a different path and our pools show it.

 

[jseyfert3]

I never used strips on my hot tubs or pool because I used them for an aquarium in the past, they were so terrible I couldn’t even guess what the levels were (is that 50 or 200? Who knows?). I bought a drop based aquarium test kit and ditched the strips. I could actually measure water parameters now!

So when we got a hot tub getting strips was never an option. I found this site, got the recommended kit and never looked back. I did try the strips that came with our Intex spa and they were just as terrible and useless as the aquarium test strips I’d used in the past.

So ultimately it’s not about “perfect balance” it’s about being able to measure what you need to measure and have an accurate (and usable) result.

 

[Donldson]

how would you compare test strips to the accuracy of leslies pool free tests? I've heard leslies can be very wrong

Both are about as awful as they come and neither are worth what you pay for them.

Every season we see someone who has lost hundreds of dollars on unnecessary products because they didn't recognize the value of good data. They chased problems that didn't exist or ignored problems they didn't know existed. Sometimes they even end up making the water worse and then have to dump the water they just poured hundreds of dollars of chemicals in to.

Things don't have to be perfect, I guarantee my pool never is. But if you can't measure your levels accurately then you can't know whether you pool is "close enough". And water chemistry problems don't get cheaper and easier to fix the longer they go, so finding out things are drifting before you can feel/smell/see the change in your water makes for a much quicker fix. And then your pool always seems perfect to those swimming in it. That's not overthinking, that's being proactive.

 

[zea3]

One other little thing about those "free" pool store tests, the pools stores don't offer them out of the goodness of their corporate heart. They are a sales tool. They will sell you products based on individual test results without any regard how changing one chemical value affects the others. This is a quick way to get your pool in a real chemical mess that is neither pleasant to swim in or inexpensive to fix using pool store methods.

Test strips, even if they were reliable, have too wide a range of acceptable results to be useful in pool management. It will tell you if "something" is there but not how much of it there is. For example a typical test strip lists a CYA result from 0-50, 50-100, 100-150. For a manually chlorinated pool you want a minimum of 30 ppm, but 50 ppm is the top of the acceptable range. if you are using stabilized chlorine, such as tablets, your CYA will steadily rise over time. If you are using a test strip and it is showing a result in the 50-100 range you are going to have a hard time determining if you have 60 ppm of CYA which is high but manageable if you switch to non-stabilized chlorine, or 100 ppm which is one missed chlorine dose from turning your pool green and will required draining and refilling the pool to fix.

 

[TexEdmond]

If you are using a test strip and it is showing a result in the 50-100 range you are going to have a hard time determining if you have 60 ppm of CYA which is high but manageable if you switch to non-stabilized chlorine, or 100 ppm

I never thought of it that way. With a margin of error of 50-100ppm CYA, that's the difference between not knowing if you need DOUBLE the amount of FC in your pool just to have safe water.

With our CYA test we always round up to the next 10, which means even if it's actually lower and we guess high, our FC levels are at most 1ppm higher than the minimum safe level, (which is a no-no zone anyway) and the recommended range shifts up 1ppm as well. That is demonstrably safer and still very economical.

 

[jark87]

There’s a certain “confidence” that comes with knowing how to manage your pool, and that starts with a quality test kit. Like many others have said, it’s super easy and I don’t spend more than 10 minutes a week testing. I’d equate the test strips to the old “idiot” warning lights that cars had before all of the high-end diagnostics. Yes, the oil light would come on, but it only really told you that you had somehow lost most of your oil. And it was usually too late to avoid the damage already caused.

 

[emac]

I tried the Color Q electronic tester and some test strips. The color Q gave out after a few seasons. I decided to buy the kit suggested on here. I quickly noticed the CH and CYA were way off on the color Q. Test strips were a waste.

I have found if you take the time to fully understand the chemistry and how the different tests interact to make the saturation level, it will become easier. For example, my CH is 400, due to my well water. My TA always wants to stay low. After fighting it for a season I decided to let the TA stay lower which helps keeps the pool balanced at close to zero, when the PH is around 7.5. The color Q came with a really neat slide ruler to check water balance/saturation. The TFP app does the same thing, but for me just playing with the slide rule lets you see how the tests interact with each other . The more CH goes up the lower TA or PH need to be. Here is a link to the slide chart. I am sure there are others, but this is the one I ended up with. Fun to play with.....at least to old school people like me.

Saturation Index Calculator - 1506 - LaMotte

This is a LaMotte Saturation Index Calculator replacement part. The Saturation Index Calculator is a simple way to calculate the corrosive tendencies of your pool water.

www.poolweb.com

 

[Selenap]

I don’t worry about my saturation level because vinyl. But I do change numbers on the app to see what would happen to it. Like my calcium is 50ppm which is pretty much non existent. I’ll put in 500 just for fun to see how much it changes. Than 5000. Than fool with the other numbers to see how the saturation number reacts. Lol. Calcium at 5000 I’d raise the water level dumping 1200 pounds in btw. Probably get put on a FBI watch list too.

 

[mkolb]

new pool owner here. I was speaking with my wife about the test kits and she said "it doesn't have to be perfect, you're thinking too hard about all this" referring to getting the pool balanced. I didn't really think about that. I understand the test strips aren't very accurate but they are cheap and does it really matter if your pool isn't PERFECTLY balanced? I know alot of you guys are very adamant about having your pool perfectly balanced so can you guys explain why it matters to have it dialed in to an exact point vs a ballpark range with test strips. I'm easily convinced it should be perfectly balanced so I need some ammo to convince my wife

I learned the hard way.. I used test strips and Leslie's free test 5 years ago. I spent $500+ in chemicals from Leslie's and my pool still looked like Crud.. In addition to that, my PH got so low that I cracked my heat exchanger; that was not cheap to replace... Since I have followed this method; I only buy liquid chlorine and acid... Pool has been perfect for years and is much cheaper to operate.. Buy the test kit; well worth it... The reagents will typically get me through two years; only have to purchase a few reagents each year that I use more often..

 

[emac]

@mkolb, I agree TFP method is simple and effective. I like keeping my pool balanced not only for the plaster, but for the heater as well. In five years all I have replaced is the pump housing that cracked, and that is a common failure on my model. With the cost of chemicals today, it pays to keep it simple.

 

[V___25]

Absolutely perfectly balanced? No. Pretty darn close? YES! My son and I have super sensitive skin and before I got things TFP-balanced, the pool made his feet and hands itch and he never wanted to be in for more than 30 minutes. But now, he'll be in for hours and he doesn't even mention his skin.

And for more anecdotal evidence, when we first bought the house and I was still reading all the stuff on TFP, I was using guess strips which measured 0 CYA constantly. So I was like ok cool, more tabs it is!
At some point, I took a water test to the pool store and it came back with CYA of 150 which they said was ok. So then I smartened up and decided I'd better go on all in on this because I had values of 0 and 150. I finally landed at CYA of 110 with my own kit. My CYA is now at 50 but moral of the store is that between guess strips and pool stores, you really have no idea what you are working with.

Now, it's actually very easy. The only thing I've added to the pool all season is liquid chlorine and some baking soda.

Oh and my local pool stores (not a Leslies or a chain) stopped doing free water testing. Now it's $5 unless you buy something, then it's free. So they absolutely expect to sell you stuff after testing your water.

 

[CraigChing]

You got a lot of answers about pool store testing and test strips, but I’m not seeing any answers to the title of your post. Is the FAS-DPD really necessary? I would say yes. Free Chlorine (FC as we abbreviate it) is the most important parameter of a “balanced” pool. If you use test strips or pool store testing, or the OTO test, you’re sacrificing the knowledge of the most important part of pool maintenance.

Now, do I always try to be precise hitting my numbers, even FC? No. I let my FC slide a bit sometimes because I’m lazy, but because I know my pool so well from *accurate* testing, I know what I can get away with. But I always test chlorine with the FAS-DPD test.

Is my pool always perfectly balanced? No. I have high TA fill water, so unless I get a lot of rain, my TA sits > 100 most of the summer. That’s ok, my kit is accurate enough to help me maintain pH by adding acid.

This is what a good test kit and experience does for you. It gives you accurate (enough) knowledge and with that you can maintain your pool in a sanitary and predictable way.

 

[CraigChing]

Oh and my local pool stores (not a Leslies or a chain) stopped doing free water testing. Now it's $5 unless you buy something, then it's free. So they absolutely expect to sell you stuff after testing your water.

At least now they’re being honest about their business!

 

[TexEdmond]

At least now they’re being honest about their business!

Hey man... It can still be a loss leader and they can charge $5 for it... That's the exact reason why I have to limit my visits to Harbor Freight...

I’m not seeing any answers to the title of your post. Is the FAS-DPD really necessary? I would say yes

This gets directly to your question in the subject line. The DPD powder test gives us either 0.2 or 0.5 (depending on test kit) resolution for FC and CC up to very high levels. There's tons of margin built into that CC test. I often see a slight color change for CC and log 0.5ppm CC when I know for sure it's probably 0.1 or 0.2. The important thing is, it doesn't take me TWO drops to clear the sample. That'd mean I had a serious problem, and that kind of direct measurement helps us determine when to start or stop slamming an algae bloom.

 

[Tcadwall0]

I kept an above ground intex pool for 4 yrs before I had an inground put in this year. Those first 4 years I relied on Leslie's. But I spent more on chemicals then (and even drained the pool a couple times) than I do now. I had quickly upgraded the pump filter to a .75hp pump, sand filter, and SWCG. But while those upgrades helped a lot on maintenance, I still was constantly buying chemicals they recommended.

I am confident that their advice put me in the eventual situations where I needed to drain and re-fill. When I had a FG in-ground pool put in this year, I knew that draining and re-filling would no longer be an option. When I started my normal routine of taking my water to them for testing, I wasn't feeling comfortable with the pattern.

I found this forum. I read just about every article. I started reading threads. I read. I bought in on the test kit.

For one thought... It is more convenient to spend a couple minutes each morning taking the 3 main readings myself... FC, CC, pH ... rather than run to the store for that.
Second thought... Curious - how far off could they really be? Well I answered that more than once after I got my own test kit.... and don't think the strips are better.

Weekly, or after a good rain, or a refill (since my dogs are in and out taking gallons of water at a time) I re-check the rest of the levels. That takes an extra 10 minutes maybe.

I was asked earlier today by a co-worker that is thinking about getting a pool.... "What do you spend per month on chemicals and time for maintenance?" I told him about this site/forum. And told him that since I bought the test kit, and employed this way of managing the pool I probably spend about $30/month. I purchase Muriatic Acid at Lowes every couple of months. I purchase Liquid Chlorine at Wal-Mart every 3+ months (I do have a SWCG, but occasionally weather / bather load overwhelms the SWCG). I have also adopted the Borates methodology, and so I have bought some Borax here and there.

Honestly - with 2 dogs swimming every day? My chemical usage is next to nothing, and my pool is sparkling clear. You can see as well across the entire 36' length with goggles as if you were not in water.

I know that was long-winded. But here is what it boils down to:
The methodology of this site will likely save you $100 / month over the pool store. Pool store OR test strips - you will be coming back here when you have out of control algae or some other issue. This methodology is based on you having a standard quality test kit. That is the only consistent thing that will give you answers, and when you need assistance on this forum, that is the only consistent thing that people wanting to help will trust to give you the next step.