Greetings from South Florida

[jdp39]

Hi all! I am a veteran of pool wars here in Fla for the last 12 years and have lurked around the forum for quite some time. Finally took the plunge because of problems that seem to defy what all of the "experts" seem to say.

Some well educated, experienced folks on the forum for sure and I hope to advance my understanding plus perhaps contribute some hard won experience dealing with hot weather pools here in the land of the Subtropics.

 

[crookm11]

Welcome to TFP!

Looking forward to hear about your experience.

 

[jdp39]

Ty! Just wish the pools were all sunshine and roses.

 

[Butterfly]

Welcome to TFP

 

[jdp39]

Have read thru all the threads I can find related to phosphates in pool water and the best I seem to be able to do is over a year old. Any new info come to light relative to warm water (> 85 deg F) pools? Serious question w/ good reason. Thanks!

 

[Bama Rambler]

The best info you can use, is that if the pool is properly chlorinated, phosphates aren't an issue.

 

[jdp39]

Ok - here we go then because the pool we have here will grow algae from a crystal clear state. With all balance parameters dead in the window and a FC +1 over required. If chlorination alone would keep this from happening it would be a non-issue. Taking the advice posted here over a year ago regarding the CA/FC ratios, etc. yielded no improvement. The phosphate levels aren't really even that high (< 1500ppb tested) yet once a remover was used the chlorine was able to eliminate the algae and the situation would rectify inside of 24 hours. Without the use of a remover no amount of chlorine, hypo or otherwise, would eliminate the algae.
Just for reference, we had a larger pool (> 20k gal) installed in our old home and algae was never an issue. Only difference between the two, other than size, is location. The home we moved to is within 5 miles of three active phosphate mines. In addition, the airborne phosphates in this area will allow our pool cage to go green in full sunlight. We have never had that issue elsewhere.
Sort of defies the "chlorine will take care it" statement. Whatever this is will grow faster than the chlorine can kill it, regardless of the amount or type of chlorine used. I guess we're in that 1 in 5000 fringe.
If you need I could do a full test today just to give real time, accurate numbers.
Thanks for the interest.

 

[Bama Rambler]

How long do you run the pump per day?
Are there any dead spots in the pool that doesn't get good circulation?

A full set of test results would help. And how you're getting them.

 

[susa]

>> could do a full test today just to give real time, accurate numbers.

please do and post also details on your equipment and how you use it.

personally, with FC 4, TA 50, CYA 60, CH 360, PH 7.7, Borates 40 and running pump 10/24 hours (4 days/3 days) appears to maintain phosphates below 100. SWCG is on 20% for 5 hours(1 hour runtime) 4 days/week.

 

[jdp39]

@Bama Pump runs approx. 7 hrs during winter months and 9-10 hrs in summer (may - october in Fla.)
As far as dead spots, I spent quite a bit of time adjusting returns to get good circulation and to avoid hydraulic wear of pool surface so, no, not any dead spots. The blooms don't seem to start in any specific location.

Test results from my home kit, an Aqua Chem Pro unit, are what I usually go by. If something seems amiss, those results are invariably backed up by the more elaborate methods used by any of my local pool professionals. Phosphate levels are tested with an AquaTrend phosphate test kit (the only one I could readily get my hands on).
Unless you can recommend something different....

@susa Please explain what you mean by "how you use it"....

 

[susa]

>> mean by "how you use it"

see the sigline? most of us here post equipment and describe how many hours and what kind of use/programming.

 

[jdp39]

Ty susa saw that and was editing when you posted ; )

 

[jdp39]

Balance a bit out from holiday weekend but as follows:
FC 3.5, PH 7.5, CA 40, TA 90, CH 240, PO4 250ish

By my calc at the pump runtime it should be turning the pool 3+ times daily. Have adjusted and will grab new #s in a couple hours but they should be in line. Thoughts?

 

[Bama Rambler]

My initial thought is that you're letting your FC get too low for your CYA at times. That 3.5 is pretty close to the bottom of the recommended range and since you're using tabs it's likely that your CYA is higher than that.

 

[jdp39]

As I say, it's the day following heavy use from the holiday weekend and the pool is a bit off.
I am curious tho, is the CYA as it comes from trichlor not readable in a CA test? Or is there a different test that will show it? As the FC is usually about 5 (any higher and it smells like the pool at the Y) this 3.5, like you say, is on the bottom. For just that reason we tend to keep the CA on the low side. I really don't see much of a CA rise here during winter/spring as we lose quite a bit of water from evap. so it pretty much evens out w/ refill.
Unless I'm not seeing ALL of the CA due to errant testing. I will ck for threads on that.
I am still curious also why the addition of phos remover has such a startling effect.
Thanks for the interest.

 

[chem geek]

I am still curious also why the addition of phos remover has such a startling effect.

Because if you only have orthophosphate in the pool and not many organic phosphates then a phosphate remover will significantly slow down algae growth since they need phosphates to grow. So then the algae growth rate becomes much slower than chlorine's kill rate.

However, are you saying that before adding the phosphate remover you were maintaining shock levels of chlorine with the FC around 40% of the CYA level and the algae would continue to grow -- it wouldn't even turn from green to gray? Or are you saying that after lowering from shock level to an FC of around 7.5% of the CYA level that the algae would then come back? Yellow/mustard algae can come back at this level (it would need an FC that is around 15% of the CYA level to keep away) which is why one must kill it off completely.

I've had 3000+ ppb phosphates in my pool normally at 85ºF-90ºF temperature and though the pool was very reactive if I let the chlorine get too low, it was always algae free if the proper FC/CYA ratio was maintained. Others have similar experiences.

If you are using tabs, then your CYA is likely climbing and I suspect that your CYA reading is wrong from your test kit. You should really have a better test kit, either the TFTestkits TF-100 or the Taylor K-2006. If you are using Aqua Chem 6-Way Test Strips then they are next to useless and I don't care what other pool stores or professionals you are comparing against since we've seen over and over again how they are often wrong as well. Even if you are using a drop-based test kit (such as the Aqua Chem Pro from Walmart), the chlorine test is likely still DPD comparing colors and is not as accurate as a FAS-DPD test kit (and I think in that test it's TC only and may have 50 ppm CH resolution compared to Taylor's 10 ppm). See this post for a comparison of test strip vs. FAS-DPD drop-based test kit resolution. The accuracy is even worse for test strips than shown, especially for the CYA test (and test strips can't even test for CH). Even for DPD drop-based chlorine tests, some have found it to be less accurate than FAS-DPD (which can measure to within 0.2 ppm when using a 25 ml sample size).

You mentioned using Trichlor and your sig says you have an inline chlorinator (tabs), but for every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. So even with a 2 ppm FC per day chlorine usage, Trichlor would increase CYA by over 35 ppm PER MONTH if there were no water dilution. If you find that your test kit is not having the CYA increase significantly over the months, then there's likely a problem with the that test. Without an accurate FAS-DPD chlorine measurement and an accurate melamine turbidimetric test for CYA, I don't think you can conclude anything about the FC/CYA ratio being the reason for not preventing algae growth.

 

[jdp39]

100% agreement. We had been using a non-stabilized tab in prior years. After the spike in chlorine prices ($100 a bucket) we went back to liquid. Just this winter went back to tabs and after re-reading the whole phosphate thread once again I went out and pysically cked and sure enough it's trichlor.

We got away from CA some time ago as it never really seemed to cut our usage of chlorine at any level. Apparently a real test kit is in order, even tho we have never used a test strip as our kits have always been reagent, and I presume we will be back to liquid until evap loss drops the CA level again. In the meantime I will have to ck if we can get straight hypochlor tabs or if the stabilized version is all that's available.
Other than attempting to keep the chlorine stable in the sunlight is there any other real need for CYA?
I am also interested in the Borax approach but the initial expense is out of the question at the moment. I should be able to test in the next day or so and I will post the findings here.

Once again I am in total agreement and thank you all for your input.

 

[chem geek]

I presume we will be back to liquid until evap loss drops the CA level again. In the meantime I will have to ck if we can get straight hypochlor tabs or if the stabilized version is all that's available.
Other than attempting to keep the chlorine stable in the sunlight is there any other real need for CYA?

Evaporation will not lower CYA or anything else in the pool since only water evaporates. You can only lower CYA by dilution of the water, so physically removing water (with everything in it; not via evaporation) and then filling up with fresh water (tap water has no CYA in it).

You need CYA not only for protecting chlorine from degradation from sunlight, but also to moderate chlorine's strength. So even if your pool is covered or not exposed to sunlight, you should still have some CYA in it, though perhaps only 20-30 ppm. If exposed to sunlight, then you should have more, usually in the 40-50 ppm range.

 

[jdp39]

@geek That should pose no real problem, I can simply vac to waste or open a dump valve.

I am somewhat confused why chlorine tabs have stabilizer in them. If CYA is introduced to the pool and it does not degrade, breakdown or otherwise leave the system why on earth would you need a steady stream introduced along with the chlorine? Especially at the rate apparently given. Other than to sell more chlorine that is. ; )

 

[chem geek]

The main reason Trichlor pucks/tabs are so popular is that they are the only reliable slow-dissolving form of chlorine. There are also Cal-Hypo tabs, but they require more fillers to bind them together and tend to fall apart as they get smaller. Unfortunately, there is no slow-dissolving tablet form of chlorine that does not have the side effect of increasing CYA, as with Trichlor, or CH as with Cal-Hypo. There is also Dichlor, but that's only in powdered form and increases CYA even faster than Trichlor for the same chlorine amount. That's just the way the chemistry works.

There is a solid form of chlorine, lithium hypochlorite, that doesn't have these side effects, but it only comes in powdered form and it is very expensive.

So that just leaves sodium hypochorite aka chlorinating liquid or bleach. It's great at not having significant side effects (it increases the salt level) but unfortunately cannot be in very concentrated form since it degrades more quickly. So you are mostly buying water which means more to carry, but at least it is priced accordingly and is usually the least expensive form of chlorine though in some areas Cal-Hypo is cheaper (and I'm accounting for the pH/TA adjustment products needed with Trichlor and Dichlor when I'm comparing pricing).

For automated dosing, one has options for dispensing chlorinating liquid or bleach including using The Liquidator or a peristaltic pump or one can generate chlorine on site from salt by using a saltwater chlorine generator (SWG).