Yellow staining on pool walls (plaster)

[Mindflux]

I think this is metals staining. It doesn't brush off and appeared out of nowhere in 'streaks' in areas.


FC: 5 (Target)
PH: 7.2 (lowering TA right now which is why it's lower than 7.5)
TA: 90
CH: 450
CYA: 70
Salt: 2800
Borate: N/A (not tested)

Is there any way to remedy this? I think my numbers are doing pretty good other than CH being a little high which is typical for our water I believe (hard water!)

 

[JVTrain]

Have you tried the ascorbic acid tablet treatment on them yet? Take some Vitamin C (ascorbic acid) tablets and hold them on the stain and see if they lighten or go away. If they do lighten, you know the whole pool AA treatment will work to remove the stains, but metal sequestrants might be needed after they are removed.

Numbers look good. The slightly high CH is more than manageable as long as you know what pH level keeps your CSI in line using Pool Math.

 

[Mindflux]

Have you tried the ascorbic acid tablet treatment on them yet? Take some Vitamin C (ascorbic acid) tablets and hold them on the stain and see if they lighten or go away. If they do lighten, you know the whole pool AA treatment will work to remove the stains, but metal sequestrants might be needed after they are removed.

Numbers look good. The slightly high CH is more than manageable as long as you know what pH level keeps your CSI in line using Pool Math.

I have not tried AA yet. It just sucks they popped up out of nowhere.

Also I assume the CH is why my tile has a scaling line, and the darker spots on my plaster (I was told is CH scaling? I thought it might have been mottling?)

Also with the current numbers my CSI is -0.34. I assume since it's above -0.6 and below 0.6 I'm in good shape?

Also it seems lowering my TA to 70 from 90 and my keeping PH to a normal level of 7.5 my CSI goes to -0.21. But if I keep the TA at 90 with a PH of 7.5 The CSI is -0.06 (which seems like it would be better? further from -0.6)?

What does a CSI out of the suggested numbers mean?

 

[JVTrain]

If you look at Pool Math or in Pool School the perfect ranges for CSI are between -0.3 and 0.3. Here you should have very limited potential for scaling (high positive CSI) or corrosion (low negative CSI). Between -0.6 and -0.3 you have potential for corrosion. Between 0.3 and 0.6 you have potential for scaling. Those are the warning zones. Not bad for them to be in there temporarily, but long term kept in those ranges could cause corrosion or scaling. Less than -0.6 or greater than 0.6 will cause problems faster.

 

[Mindflux]

If you look at Pool Math or in Pool School the perfect ranges for CSI are between -0.3 and 0.3. Here you should have very limited potential for scaling (high positive CSI) or corrosion (low negative CSI). Between -0.6 and -0.3 you have potential for corrosion. Between 0.3 and 0.6 you have potential for scaling. Those are the warning zones. Not bad for them to be in there temporarily, but long term kept in those ranges could cause corrosion or scaling. Less than -0.6 or greater than 0.6 will cause problems faster.

I'm not seeing anything about 'perfect ranges'. Everything I see in Pool School and Pool Math about CSI suggests -0.6 to 0.6. But I suppose it makes sense.

Less than -0.6 is suggestive of problems for plaster, tile, stone, and pebble pools.
Greater than 0.6 is suggestive of problems for all pools.

To prevent scaling, you should keep your CSI below 0.6 at all times. Pools with surfaces containing calcium also need to have their CSI above -0.6 at all times to prevent pitting. Vinyl, fiberglass, and painted pools can safely have a significantly negative CSI. The CSI is very sensitive to PH changes. With surfaces containing calcium you normally try to balance your CSI fairly close to zero so that future PH swings will still leave the CSI within these bounds.

It's just odd that the numbers I'm trying to get at rest at about -0.22 (so, in the 'perfect range').. however if I drop my CH to a preferred level I'm suddenly at -0.32. It seems like a SUPER FINE balancing act.. if all my numbers are in the suggested ranges I am not in the 'perfect range' zone.. I'm just outside it.

If I raise my PH to 7.8 from 7.5 I'm suddenly at -0.05 ... though....(assuming I could get my CH down to 350)

 

[JVTrain]

The "perfect ranges" are just what I called them. They are ideal, but ideal is not always practical. You're safe between -0.6 and 0.6. You're even safer between -0.3 and 0.3. You're even safer than that if you're between -0.05 and 0.05, but is that realistic to maintain? No.

 

[Mindflux]

The "perfect ranges" are just what I called them. They are ideal, but ideal is not always practical. You're safe between -0.6 and 0.6. You're even safer between -0.3 and 0.3. You're even safer than that if you're between -0.05 and 0.05, but is that realistic to maintain? No.

It doesn't seem even -0.3 to 0.3 is realistic to maintain (easily) playing with poolmath.

It seems to me these keep me in the perfect range:

FC: 5
PH: 7.8
TA: 60
CH: 450 (can't fix this without a partial drain)
CYA: 70
Salt: 2900

CSI: -0.05

If I try to keep the pH at 7.5 and all the others the same, my CSI becomes -0.32 (outside 'perfect range'). Raising TA to 70 would drop that to -0.22. Like I said seems like a juggling act.

 

[JVTrain]

It doesn't seem even -0.3 to 0.3 is realistic to maintain (easily) playing with poolmath.

Then don't. Why the need to keep pH at 7.5? The only time you should lower it is when it goes above 7.8. You're over analyzing it. Your chemistry is fine with a pH anywhere between 7.5 and 7.8.

 

[Mindflux]

Then don't. Why the need to keep pH at 7.5? The only time you should lower it is when it goes above 7.8. You're over analyzing it. Your chemistry is fine with a pH anywhere between 7.5 and 7.8.

I don't need to keep it at 7.5, though if I keep it low it takes a while to get back over 7.8. If I keep it at 7.8 I'd be adding MA every day as my spa causes enough aeration to go off the OTO color chart quite easily. It doesn't seem there's a way for me to prevent that as my spa returns are plumbed in together with the pool return and the Jandy actuator can't change position part way through a schedule from what I'm told so there's no way for me to turn off the spa return unless the whole system is off or I go manually move the actuator.

Pool runs from 9AM to 6:00PM every day, which means the spa return does too. Spa jets aerate and then the water 'overflow' to the pool causes more aeration. It would seem in my best interest to attempt to keep the PH on the lower side and let it climb, rather than always fight at the high edge?