Help with recommendations for pool levels

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dteirney

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Feb 15, 2015
18
Auckland/New Zealand
Hello from New Zealand. I've been reading through Pool School and various other great articles and forum threads here at Trouble Free Pool. I've been going to the local Bioguard stocking pool store for years and simply followed the instructions on the print outs from there. Needless to say I'll be making some changes to that routine - primarily changing to use sodium hypochlorite rather than trichlor granules (Bioguard PowerChlor).

I've just finished a shock cycle after getting back from a 2 week holiday a week ago and finding the start of an algae bloom across the bottom and partially up the sides of the pool. That's was all sorted about 3 days ago, with the help of some flocking to help clear the water without needing to run the pump 24/7 for as long. I haven't put any additional chorine in while waiting for it to drift down but today I noticed a green tinge appearing on the floor of the pool where the water circulation might not be great.

UV levels here in New Zealand are very, very high over the summer and the sunlight periods are long. Up at 6am, down around 7:30pm. I'm wondering if that means I should look for a target CYA that's perhaps higher? I think these are the levels I should perhaps be aiming for but looking for advice here. With known numbers I can plug them into the Pool Math page with more confidence.
PH - 7.7
TA - 100 (is this still too high if moving to use bleach)?
CH - 100
CYA - 60

I've ordered a TF-100 test kit but it won't arrive for a while as I had to get it freight forwarded from the US. Prior to being able to do the testing myself I've got a sample from some test strips and the pool store.

Test Strips (Aqua Check)
FC: 3-5. Perhaps 4
PH: 7.8 - 8.4. Perhaps 8.0
TA: 120-180. Perhaps 150.
CH: N/A
CYA: 100-150. Perhaps 120. Crazy high...

Pool Store (various reagents and color comparisons)
FC: 4
PH: 7.9
TA: 140
CH: 128
CYA: 59 (black dot test)

I've used the pool store numbers for Pool Math to start balancing the pool using a fresh purchase of 20 litres of 12% sodium hypochlorite. I have lots of evaporation over summer and lots of overflow in winter, which has probably kept the CYA in check since I've been using trichlor up until now.

Also looking for guidance on pump run time. Should it be based on how many times the pool water volume is turned over each day? Our pool is quite small with a relatively new 1.5HP pump. I can control the timings on and off easily with a Belkin Wemo in the pump power socket.

Thanks in advance for any advice provided!
 
hi, and welcome to TFP
i am in Australia so i know what you mean about the ultraviolet
until you receive your test kit you are in a bind trying to guess what your results are especially CYA
if you maintain your pool daily you can run a higher CYA, but if you get algae it will be harder to clear
evaporation doesn't remove any chemicals from your pool only distilled water, overflow and splashout will though
i run my pump 7 hours day in summer, 2 hours at 10 am, 2 hours at 4pm and 3 hours at 11pm
this is mainly to skim the leaves off
5 hours a day in summer and 2 in winter would probably be ok
you are going to love how easy it is to maintain your pool the TFP way
 
You should start working lowering that TA to roughly half of what is. Add acid to lower PH to 7.2...........aerate the water.......................lower PH AGAIN. Repeat as required.
 
Hi dteirney,

It sounds as if you certainly need that TF100 test kit.

It sounds to me as if the shock treatment never really got rid of the initial algae problem. If you dont keep the FC to CYA ratio correct, then what you experiencing with the re-emergence of algae isn't surprising at all.

Read up on the SLAM process, and if you strictly follow it, you will be rid of the algae. Tip of the day: Algae can hide behind light fixtures, in autofill system and in any water feature pipes that have been unused for quite some time. So check those out!
http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shocking

If you havent bookmarked this page already... here is a link to the FC/CYA chart
http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

You will need to use this tool to figure out how much chlorine to add in order to maintain FC
http://www.troublefreepool.com/calc.html

When you have completed the SLAM and your pool is algae free, use the TFP recommended levels and you will not have anymore problems at all.
http://www.troublefreepool.com/content/134-recommended-levels

In the meantime, until your test kit arrives, I would recommend to add about 5L chlorine each day. This should help in at least
limiting the growth of algae until you can attack it properly.
 
Thanks for the advice everyone. I decided that the best course of action was to not do anything too drastic until the test kit arrives so I have accurate and repeatable readings. Especially with regards to chlorine levels since the test strips (which are a bit marginal anyway) don't read anything higher than 10ppm.

I've been adding ~900ml of 12.5% liquid chlorine every 2 days and this has kept the chlorine levels around 5ppm on the test strips. 900ml represents an increase of ~4ppm for the size of my pool, which (I think) means I'm getting about the expected 2ppm drop each day if the levels are staying mostly consistent when I measure each 2nd day.

I've also deep cleaned the filter based on the instructions elsewhere here at TFP. A lot of milky white water came out during that process - cleaned for probably 25 minutes before it ran clear.

Water (and pool in general) is currently crystal clear following vacuuming to waste of some of the heavier dirt that was still sitting on the bottom of the pool.

I'll report back after the TF-100 test kit arrives and I've got some accurate readings. Should be middle of next week (fingers crossed).
 
dteirney said:
Thanks for the advice everyone. I decided that the best course of action was to not do anything too drastic until the test kit arrives so I have accurate and repeatable readings. Especially with regards to chlorine levels since the test strips (which are a bit marginal anyway) don't read anything higher than 10ppm.

I've been adding ~900ml of 12.5% liquid chlorine every 2 days and this has kept the chlorine levels around 5ppm on the test strips. 900ml represents an increase of ~4ppm for the size of my pool, which (I think) means I'm getting about the expected 2ppm drop each day if the levels are staying mostly consistent when I measure each 2nd day.

I've also deep cleaned the filter based on the instructions elsewhere here at TFP. A lot of milky white water came out during that process - cleaned for probably 25 minutes before it ran clear.

Water (and pool in general) is currently crystal clear following vacuuming to waste of some of the heavier dirt that was still sitting on the bottom of the pool.

I'll report back after the TF-100 test kit arrives and I've got some accurate readings. Should be middle of next week (fingers crossed).
Click to expand...

Sounds like a plan, and based on this post, you'll have no trouble at all. This will be cake for you.
 
The results are in. The TF-100 test kit arrived today.

FC - 9
CC - not tested. Accidentally tipped it out after doing FC. Won't make that mistake again :)
PH - 7.7, maybe 7.8.
TA - 160
CH - 175
CYA - ~100. Was just over 100 before diluting 1:1 and then between 45 and 60 for the 3 times I tested after diluting.

Clearly CYA is too high and I'm looking at a pretty substantial drain to bring that down. What's the best way to remove and then replace that much water for a vinyl pool? The skimmer box can only pull out two, maybe three inches before it just starts sucking air. I could possibly drain via the return line as that aims down at 45 degrees for a couple of feet into the pool. Or just drain directly from a vacuum hose over the side of the pool. I'm not sure how much I can safely take out in one go though.

Taking out several inches and then refilling, mixing and then draining again will lead to needing to take out more than 50% total of the water put back in (since a portion of the new water will effectively get taken out during the next drain cycle).

Would this be a good opportunity to "super backwash" the sand / glass filter or is that way too much time spent backwashing?
 

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I drained about 40% of the pool yesterday (430mm from 1100mm of depth), refilled from our hose and ran the pump for about 3 hours last night and another hour this morning and re-did the CYA test. I diluted the pool sample 1:1 with tap water expecting the result to still be more than 50ppm. I measured 35, 40, 35, and 45 off the side of the CYA test tube for 4 tests so I'm guessing the CYA is now about 70-80 and still too high.

I assume that as the CYA comes down the testing into the 50ppm range will get more accurate (so the original CYA was probably higher than 100ppm because with the draining just done I should have seen about 60ppm).

I'm about to start another drain cycle taking out about 30% and will then re-circulate and do the test again. Is this still the right approach to keep taking until the CYA is around the 50-60 level?
 
Yes, continue to replace water.

The CYA test with dilution is not at all precise, it just gives you a rough indication. Since your CYA level appears to be below 100 at this point, you should go back to doing the test without dilution for the better precision.
 
I just finished draining 20% and have started to refill. Once the pool is full again I'll circulate for 4 hours or so and part of tonight and then see what the reading is with an undiluted CYA test first thing tomorrow morning. If it's below 60 I'll probably leave it there given the high UV levels we have here in New Zealand.
 
After replacing more that 50% of the pool volume I've finally got the CYA level down to something sensible.

Current levels from the TF-100 test kit:
PH - 7.9
FC - 5
CC - 0
CH - 125
TA - 90
CYA - somewhere between 50-60

With the current readings the only thing I think I need to do is lower the pH, aiming for 7.5 (mainly because that's one of the coloured blocks on the Taylor test kit so easy to see how close it is). The Pool School suggests 7.7 or 7.8 is ideal but I can't find any reasoning why. Some other sites I've looked at seem to recommend a lower ideal pH, e.g. 7.2 - 7.6 (and even some TFP forum threads suggesting 7.4 - 7.6 as well). Human eye pH seems to be less than 7.7, depending on what you read, but typically most research seems to suggest <= 7.4. I'll start with adding 200g of dry acid and measure again tomorrow morning.

Monitoring the free chlorine level should be easy with the daily test by just checking that the level is at least 5ppm (the darkest yellow block). Hopefully after a little while I'll know how many FC ppm the pool is consuming each day (not being used much at the moment). Tonight I'm putting in ~500mls of 12.5% liquid chlorine to take it up to the target of 7ppm for a CYA of 60.
 
The PH tends to go up over time, more so if you try to keep it low. By aiming for the higher end of the range you won't be fighting against the natural PH rise and your chemistry will be more stable. The recommendations elsewhere for keeping PH low are based on a fifty year old rule of thumb about how the chemistry works that simply isn't true when you have CYA in the water.
 
Thanks @JasonLion for the information about the PH recommendation. Thanks also to others that have chimed in with support encouraging me that I'm on the right track.

Regarding PH it would seem that if I keep it between the 7.5 and the 7.8 coloured blocks on the daily Taylor test kit then everything should be fine. If it ever drifts above 7.8 then simply add enough dry acid to take it down to 7.6.
 
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