Going away, SWG and suspect algea outbreak

[jesper]

Hi,

I'm a new pool owner, pool was filled about 5 weeks ago. Up until last week I was manually adding dichlor and dry acid to keep the pool balanced, and didn't have any issues.

Last week I added salt to 4000 ppm in preparation for the installation of a SWG, after adding the salt I had issues with FC dropping much faster than usual, and a few times it had dropped to zero before I got more dichlor added.

Mid week I noticed the water also started to look a bit dull, not being sufficiently familiar with the pool, I didn't think it could be algae, but instead added a 'clear tab' to the skimmer, the next day the water started looking better, so I thought it was just dust or something.

The SWG was installed Thursday , and the installer set it to 20% output as we have a cover on the pool at all times it is not used. Friday evening FC had dropped to 0.6, so I cranked the SWG up to 100% and increased the pump run hours a little to ~7 hours a day. Over night after the pump running for 5 hours FC had increased to 1.6 Saturday morning.

We're out of town for a family event over the weekend, but reading TFP yesterday I got really worried if we have the start of an algae outbreak, especially as we're going away on Tuesday evening. Not being there to look myself, or do a water sample I had a friend drive by and put the pump on manual so it and the SWG runs 24 hours a day until we're back Sunday evening - while the SWG probably cannot raise the FC enough to do a SLAM, it has got to help - PoolMath says running it at 100% for 24 hours should raise FC by 17, which of course will be offset against any drop due to FC being used.

We will be back Sunday evening and I have until Tuesday evening to do something, before being away for 12 days, what do you suggest I do ? Specifically
1) What should I do between Sunday and Tuesday, I guess I need to SLAM - but 2 days is likely not enough to get any kind of conclusive result.
2) What do I do after Tuesday, keep the pump and SWG running 24 hours a day at 100% SWG output while we're away ? I didn't have enough time between the SWG being installed and us going away to get an idea of what setting I need it on to keep FC at a known level.
3) Are there any risks if I end up with very high FC levels due to running the SWG at 100% whilst we are away ?
4) Do I close the cover whilst we are away ? If possible, I'd like the cover closed, it is a safety cover and I would feel much better knowing that nobody can fall into the pool whilst we are away.
5) I have an automatic pH system with a pH probe and an acid dosage system, it came with the SWG. I've read in the SLAM thread that pH tests aren't reliable during SLAM'ing, so I'm concerned if the automatic system might overdosage the acid if the pH probe yields incorrect results due to high FC levels. Should I turn it off ?

Saturday morning before we left the test results were
FC 1.6
CC 0.2
pH 7.4
TA 110
CH 425
CYA ~20
SALT 4000
Temp 31 Celcius / 88 Fahrenheit

(edited to provide more information)
- The pool is an in ground pool with beadcrete plater and marble covered steps, it is 2.8m x 8.5m with an average depth of 1.6m (9.2 feet x 28 feet x 5.2 feet ).
- The SWG is an BSV EvoLink25 with pH automation (probe & acid dosage system).
- The cover is an opaque PVC cover with rails by the side of the pool, resting on the water. Covering the surface of the pool completely, so I should lose very little FC due to sun exposure.
- Got a 1HP pump with a sand filter, backwash last done 6 days ago, filter pressure just after backwash was ~16 psi, it was ~18 on Friday.

Sorry for the long post, but I'm very confused and concerned.

thanks
Jesper

 

[Tena]

Your TA seems high and your CYA is low causing chlorine loss.

My SWG runs 24/7 at 60% currently.

Not knowing what size pool, or type SWG, or cover type you have, it may be hard to get a good answer. But my guess would be, crank that swg up if you're leaving and can't get anything else done.

 

[jesper]

Your TA seems high and your CYA is low causing chlorine loss.

My SWG runs 24/7 at 60% currently.

Not knowing what size pool, or type SWG, or cover type you have, it may be hard to get a good answer. But my guess would be, crank that swg up if you're leaving and can't get anything else done.

Thanks for getting back to me.

TA was initially much higher around 240, and I got it down to 110 by adding acid and aerating, I can restart that when I get back Sunday evening - but if I cannot make accurate pH measurements due to SLAM'ing, it might not be the best idea ?

I'll double check CYA when I get home, the reading is a couple of weeks old, and it has probably increased some by adding dichlor, PoolMath says the 2.1 kg of Dichlor I added should have increased CYA by 31. Once I've measured, I can buy some cyanuric acid Monday morning and bring it up to 60-70 as recommended in Chlorine / CYA Chart - Trouble Free Pool for an SWG pool.

The pool is 2.8m x 8.5m with an average depth of 1.6m (9.2 feet x 28 feet x 5.2 feet )

The SWG is an BSV EvoLink25 with pH control.

The cover is an opaque PVC cover with rails by the side of the pool, resting on the water. Covering the surface of the pool completely, so I should lose very little FC due to sun exposure.

Forgot to mention I have a 1 HP pump with a sand filter.

 

[frogabog]

I can't confidently answer your questions, but I did want to point out that you can use the 10ml sample for FC and then each drop is .5ppm. It will save reagents, and that's as precise as you need your test results to be.

Can anyone local come check the pool while you're away? Maybe someone you could teach how to use your kit and at least send you a couple reports over those 12 days?

 

[jesper]

I can't confidently answer your questions, but I did want to point out that you can use the 10ml sample for FC and then each drop is .5ppm. It will save reagents, and that's as precise as you need your test results to be.

Can anyone local come check the pool while you're away? Maybe someone you could teach how to use your kit and at least send you a couple reports over those 12 days?

Good point about the 10ml sample, I had been using a smaller sample when testing CH to save on the reagent.

Trouble is that it is peak holiday season, and most people are away. I can probably find someone that can pass by every couple of days to do a FC measurement and adjust the SWG production rate and/or pump run time. That at least should allow us to avoid a very high FC due to excessive production from the SWG.

If I can get and keep FC around SLAM levels while we are away, I can deal with any fallout when we get back.

What I'm still not sure about is pH, if I risk the automated system overdosing acid due to false reading while having FC at SLAM levels ?

 

[frogabog]

So, how often does the automated acid system dose normally? And how much? I would imagine that you could use that information to lower pH maybe down to 7.0 and turn it off. If you can get someone to come by and check to make sure its not going too high too fast, just let it rise on it's own.

 

[jesper]

So, how often does the automated acid system dose normally? And how much? I would imagine that you could use that information to lower pH maybe down to 7.0 and turn it off. If you can get someone to come by and check to make sure its not going too high too fast, just let it rise on it's own.

It has a pH probe and you set a target pH level, it then adds acid as needed to achieve the target level. I have the target set to 7.3, when I measure with the K2006 set it says 7.4 - guess the difference could just be measurement accuracy.

Don't know much more about how the probe actually works, it is the Kit Auto (pH) at https://www.bsvelectronic.com/wp-content/uploads/kit-advance.pdf

 

[frogabog]

So you don't have any real idea how often it has to add acid or how much. Hmmm... I was just thinking if (for example) you knew your pH rises by .2 every 3 days, then 12 days would be .8, therefore lowering pH to 7.0 should only leave you at 7.8 when you get back.

 

[jesper]

So you don't have any real idea how often it has to add acid or how much. Hmmm... I was just thinking if (for example) you knew your pH rises by .2 every 3 days, then 12 days would be .8, therefore lowering pH to 7.0 should only leave you at 7.8 when you get back.

In the past pH has risen 0.4 in 2 days, it is a new plaster pool, so don’t think I can leave it 12 days without adding any acid

 

[frogabog]

Well, part of the problem is that at SLAM level FC, you can't even test to check pH. So, a friend coming by to check up on it won't help much either. Can you set the automated acid to a set schedule without testing?

 

[jesper]

Well, part of the problem is that at SLAM level FC, you can't even test to check pH. So, a friend coming by to check up on it won't help much either. Can you set the automated acid to a set schedule without testing?

Don’t think so. Maybe I’m better off turning off the pH control and ask a friend to add dry acid when he comes. I used to add about 600g every 3 days, if I keep the same rate without measuring it can’t go completely off I guess.

 

[frogabog]

All this is of course if you can even reach SLAM level with the SWG at 100%, and if you actually need to SLAM.

Maybe test it over the couple days you're home at 100% and see what FC levels are. If it never goes over 10ppm (with the cover on) that's what you're going to get while on vacation and then your probe shouldn't have a problem?

Or, forget about SLAM and just try to set the SWG so that it sticks at target, have someone come by 2 or 3 times, and hope for the best? If you have to SLAM when you get home, it's not the end of the world and you can still swim.

You could always send the family on vacation without you, and you can babysit the pool at home alone. (jk)

I think your solution with the friend is likely the best option.

 

[jesper]

Thanks for all the help and advice, will see what it looks like when we get home tonight, if I can keep FC around 6-10 with SWG when we’re away, I guess it would keep the algae from growing completely out of control, and I can SLAM when we get back. But having someone to check on it a few times would be good.

Thanks again

 

[frogabog]

Good luck with this! Definitely do report back what you end up doing and how it works out. Lots of TFP peeps are asleep right now (most of the US is between 2 and 4am atm - I'm Pacific time and it's nearly 1am) so I expect you'll get loads more responses tomorrow.

Regardless of what you do with the pool, just enjoy your vacation!

 

[mguzzy]

Hi I thought I would chime in here... your CYA is way too low for a SWG pool and you are loosing FC because of that for sure (see the FC/CYA Levels).. it should be somewhere north of 60. Whether you are starting a bloom can only be ascertained if you do an Overnight Chlorine Loss Test. So... if you don't have time to get the CYA up as it will take days for the reading to stabilize,. you might want to augment your CL with some pucks that have CYA in them while you are away since both your FC and CYA are low. . Your pH and TA are close enough so I wouldn't worry too much about that. Put the cover on and deal with fine tuning things when you get back.

 

[jesper]

Hi I thought I would chime in here... your CYA is way too low for a SWG pool and you are loosing FC because of that for sure(FC/CYA Levels).. it should be somewhere north of 60. Whether you are starting a bloom can only be ascertained if you do an Overnight Chlorine Loss Test. So... if you don't have time to get the CYA up as it will take days for the reading to stabilize,. you might want to augment your CL with some pucks that have CYA in them while you are away since both your FC and CYA are low. . Your pH and TA are close enough so I wouldn't worry too much about that. Put the cover on. and deal with fine tuning things when you get back.

Thanks, that is good advice - I've never used the pucks before - should I just put an appropriate number in the skimmer before we leave, or is it better if I have a friend add a new one once or twice a week ?

As for the appropriate amount, are there any general guidelines I should follow, or should I rely on what the packaging says relative to the water volume ?

 

[mguzzy]

Sorry I don't have a specific answer for you on that one. I haven't used pucks in over 15 yrs since I got my SWG going .... As I recall I used one or two a week... but I have read of people putting in a stack of them when they go away for a spell. The Pool Math app will tell you how exactly how much contribution a puck will make for your pools size in the old PoolMath app it is at the bottom of the page, in the Newer App it's on the menu under "Effects of Adding". That should give you a ballpark figure to work with.

Just make sure you don't get pucks with an algeacide in them.. they are often copper based and the last thing we want to add to your pool is metal. If the word "blue" is in the name, its probably has cooper something in it.

 

[jesper]

Sorry I don't have a specific answer for you on that one. I haven't used pucks in over 15 yrs since I got my SWG going .... As I recall I used one or two a week... but I have read of people putting in a stack of them when they go away for a spell. The Pool Math app will tell you how exactly how much contribution a puck will make for your pools size in the old PoolMath app it is at the bottom of the page, in the Newer App it's on the menu under "Effects of Adding". That should give you a ballpark figure to work with.

Just make sure you don't get pucks with an algeacide in them.. they are often copper based and the last thing we want to add to your pool is metal. If the word "blue" is in the name, its probably has cooper something in it.

Thanks - will make sure I get ones without algeacide when I go shopping tomorrow morning. And based on the content and concentration I can use PoolMath to calculate the effect. But apart from the quantity of chlorine, I'd also have to make sure they don't all get dissolved in the first few days. Hopefully the packaging will have some kind of indication on how long they "last"

 

[mknauss]

How long pucks last is based on water flow and temperature.

Can you get a floater for the pucks? Putting in the skimmer is not a good idea as they are very acidic.

 

[mguzzy]

Hi,
...
We will be back Sunday evening and I have until Tuesday evening to do something, before being away for 12 days, what do you suggest I do ? Specifically
...

thanks
Jesper

I just reread your initial post,.. So.. it sounds like you have a few days before you leave.. if that is the case.. get some CYA for the size of your pool (again use the pool math app). You should be able to get it to into suspension in an hour or so. by putting it in a sock, letting it get mushy, and squeezing it out. Some people put the sock in their skimmer baskets. The water flow in the basket has the same basic effect as squeezing but slower and you don't have to monitor it... Then once in suspension it will take days to stabilize..

Under shoot the CYA .. that is target for 60. if you overshoot you will have to drain and refill to lower it.