Filling New Pool Q's

[Texas Splash]

Just leave well enough alone for now?

The TFP position is that since FG pools are no longer fabricated with calcium product, a low CH should be of no consequence unless there is a waterline tile installed. CSI is basically N/A for us. However, you'll find TFP still recommends a minimum CH of 250 for FG pools, but that's primarily to cover a wide spectrum of issues for most pool owners such as protection for some equipment, potential for some calcium product (tiles), and/or from various staining. I don't see a heater in your signature, so equipment shouldn't be an issue. If you have waterline tile and you've never had staining issues, your CH of 125 may be just fine.

 

[RookiePick]

Pool resisting pH change or was way off the chart somehow.

1740mL of 14.5% MA added and still showing the bright pink 7.8+ on the pH test. Pool math suggests a 0.7pH drop.

I ran my tap water numbers yesterday
TA 90
CH 125
pH between 7.4 and 7.6 by my estimation- very obvious colour difference to how the pool is testing.

Couple of thoughts -

I have been using the manual dose option to put in the MA and the unit is not dosing anywhere close to rate. I will manually measure and supply the next MA dose to eliminate that issue.

The sand and dirt finding it's way into the pool has some sort of effective acid neutralising component. Locally, I could only think of calcium carbonate sand or dusy but would expect that to show in my other numbers.

Finally, the pool returns are facing slightly upward. They are creating a bit of surface turbulence but no aeration as such. Could this be an issue? 8 hour per day run time. Has anyone got some images of the desired surface appearance with well set up returns?

 

[Texas Splash]

Could this be an issue?

It might. Depends on the amount of turbidity and duration. Your fill water test doesn't show any major issues, but still, occasional top-offs might be contributing the the rise in pH. Your TA, while not exceptionally high, could afford to come down a bit.

I would dose enough MA to lower the pH to about 7.2. If you have some concerns about dosing issues/results, you could go in stages until you get the calculations down and feel more confident. Once you do though, I would add enough acid to lower the pH to about 7.2 which should help pull the TA down more. I keep my TA anywhere from 50-80 depending on the time of year. The lower TA (50) seems to help slow the rise of pH.

 

[Newdude]

Did you do a patio yet ? Runoff from mine raised my PH for 6 to 8 months. When I checked it mid winter it was off the charts high when the off season rain (2 ft of 5-ish PH) should have lowered it.

 

[RookiePick]

Did you do a patio yet ? Runoff from mine raised my PH for 6 to 8 months. When I checked it mid winter it was off the charts high when the off season rain (2 ft of 5-ish PH) should have lowered it.

I have the remainder of the old patio but no water gets into the pool from that structure. There is a decent set back.

New patio on the cards but I fear I will get some big numbers coming back at me. Construction here is FUBAR'd atm.

 

[Newdude]

New patio on the cards but I fear I will get some big numbers coming back at me.

I hear YA !!!! Lol. My patio deep sixed any semblance of budget we had left, but I don't regret it one bit. I ridiculously oversized it and 'AHHHHH' everytime I look out the window or step out the back door.

It even took a whole week to wish I went even bigger.

 

[RookiePick]

Hmm...another 360mL MA and we have movement at the station (that's another Aussie thing) definitely south of pH7.8. gonna call it pH7.6

FC looks like it's on a slow build at the current setting. 2 days at FC 4.5 has rolled into FC 5.0 today. Might time nicely to bumping CYA on the weekend

 

[mgtfp]

Sounds good .

What is the SWG setting right now and for how long are you running it?

Not sure about Perth, but down here I don't need much CYA over winter.

 

[RookiePick]

SWG is running at 30% for 8 hours. 1.7ppm addition by pool math.

CYA is untested since I was a bit shy on test liquid volume the other day. Working on it being a 30 for practical purposes ATM.

Planning to add 300-400gm more CYA over the weekend and move to the 40 or 50 range. Will drop another bag of salt in too and push that number to 4300-4400ppm, just to have a bit more headroom from minimum.

Things looking pretty good ATM, just have the sand issue while waiting for the landscaping to happen.

Cheers for all the help so far!

 

[RookiePick]

Pool accumulated another 0.5FC over the past 2 days

FC - 5.5
CC - 0.0
pH - 7.6 (left the dosing unit on by accident, not sure if it added anything)
CH - 125ppm

Weekend plan:
Add 400gm CYA
Add 20kg Salt
Add 4kg Cal Chloride - dissolve in bucket of pool water and add at returns?
Run the robot a bunch of times and try and break the back of the sand accumulation.
Measure out the pool blanket box dimensions on the ground and try and get a consensus with the wife on installation distance from pool edge.

Received the service manual from the manufacturer of my eyeball returns. Will have a play with how they are facing. They work exactly how I thought but didn't think there was any point forcing anything in case it was a random LH thread or something.

 

[mgtfp]

Add 4kg Cal Chloride - dissolve in bucket of pool water and add at returns?

Yes, that'll work.

Calcium Chloride gets quite hot when it dissolves in water. I usually don't dissolve more than 1kg of CaCl₂ in a 10l bucket of water so that it doesn't get too hot. Some prefer to add it straight to the pool for that reason, but I prefer pre-dissolving.

Make sure that you turn off the SWG when adding NaCl or CaCl₂. Let the pump running and turn the SWG back on when everything is well mixed in.

Keep in mind that the 125ppm CH of your fill water can be enough to let the pool CH slowly creep up in summer when topping up evaporated water (Ca doesn't evaporate with the water and stays behind) with fill water that contains calcium. It really depends on how much evaporation losses versus rain (with subsequent draining when the pool overfills) you get.

 

[RookiePick]

Yes, that'll work.

Calcium Chloride gets quite hot when it dissolves in water. I usually don't dissolve more than 1kg of CaCl₂ in a 10l bucket of water so that it doesn't get too hot. Some prefer to add it straight to the pool for that reason, but I prefer pre-dissolving.

Make sure that you turn off the SWG when adding NaCl or CaCl₂. Let the pump running and turn the SWG back on when everything is well mixed in.

Keep in mind that the 125ppm CH of your fill water can be enough to let the pool CH slowly creep up in summer when topping up evaporated water (Ca doesn't evaporate with the water and stays behind) with fill water that contains calcium. It really depends on how much evaporation losses versus rain (with subsequent draining when the pool overfills) you get.

Maybe I'll keep my powder dry, literally.

Although...It's only a bump to approx 225ppm so there should be plenty of headroom to see what happens over summer.

Cheers for the heads up on the exothermic dissolution. I was wondering about the Cl addition in CaCl if it should be treated as a salt addition in terms of the salt cell.

 

[mgtfp]

In terms of the salt, there's certainly a difference between a 20 kg bag of NaCl and just 4kg of CaCl₂, so the CaCl₂ is certainly less critical for the salt cell. But when poorly mixed, you can also get a bit of increased CH through the cell. Probably not super critical, but I consider it kind of best practice.

 

[RookiePick]

Busy day.

Added cya and salt as above.
Salt tested 3800ppm prior to addition so it had a bit more to come into solution from my earlier test. Should pull me up to about 4400.

Will test CYA Monday but will treat as 50ppm until then.

Pool got a good brush with the salt add and let the robot tear up for a couple of 1 hour runs a bit later in the day. Can't wait for the paving to be done, the robot is pretty awkward with the weight and the sand by the pool..accidentally kicked a bunch into the pool pulling the robot out after the first run

Adjusted the pool returns..might be a bit low. Very still at the surface compared to prior. I'll have to see how the skimmer behaves over the next few days I guess



Dug another trench and prepared conduit so I can get some power to the far side of the pool easily later in the landscaping process.

Had the SWG off today and FC dropped to 4.0. Looks like the current setting is around the mark for the conditions. Turned it back on and running over night to top off and allow for the increasing CYA level.

 

[mgtfp]

Looks like you're getting the hang of it.

Curious how FC demand will change with higher CYA.

 

[RookiePick]

Looks like you're getting the hang of it.

Curious how FC demand will change with higher CYA.

Yep. I will be keeping an eye on what goes on for sure. I should push about 2.5ppm FC into the pool overnight and will see how that progresses with demand vs production on my usual cycle.



Interesting phenomenon when the SWG is producing tonight. Gas bubbles from the returns!

Water is definitely clearer than ever. I can now see an annoying "shadow" from both of the pool lights. Doh!

 

[mgtfp]

Interesting phenomenon when the SWG is producing tonight. Gas bubbles from the returns!

Good.

The cell produces Cl₂ gas and H₂ gas as a byproduct. The chlorine gas dissolves very quickly into the water and becomes HOCl, the sanitising form of chlorine, and OCl^-, and then the whole shebang of equilibrium chemistry with CYA, which grabs most of the chlorine - hence the recommended FC/CYA Levels.

The hydrogen gas just bubbles out at the nearest return.

Water certainly looks amazingly clear. You could also ask "which water?"...

Pool surface will always look a bit shadowy with the lights on, don't look for rabbit holes, just take it as your pool's character

 

[RookiePick]

I know what the shadows are. Its a refraction issue from the light trying to escape the surface. They are very even semi-circular areas of lower light.Many manufacturers have shrouds to block the light from going direct to surface to address this effect so I'll see if there is any available for my fitting and weigh up the old cost vs effectiveness etc.

The returns I have have an eyeball option that dilates with flow. Low flow, narrow opening in the eyeball to raise velocity. As flow increases the eyeball dilates and gets bigger. It's an interesting concept to me but probably turns the eyeball into a wear part - I'm guessing it has to lose elasticity as it ages. Might ask a few questions in that direction too as it seems to make a lot of sense with trying to run the pump at a slow speed but try to maintain circulation.

Very pleased with how the water is looking so far!

 

[RookiePick]

Soo sick of digging trenches...


Anyhoo.
Apparently some of the cement stabilised sand found its way into the pool



Discovered during today's brush...won't budge. Any ideas?

Random robot pic to cheer me up because I am pishedoff about the cement

 

[mgtfp]

Does it come off when scraping with a finger nail? Maybe a bit cold cold right now to dive down and try...

Wondering if scraping it with something acidic like a Trichlor puck would help? Or some dry pool acid in an old sock, tied to the pool pole. Usually we avoid dry acid with SWGs because of the added sulphate, but it could be an option if acid actually helps to clean that up.

Any ideas, @Texas Splash ?