Should I drain the pool now?

[FS2019]

I recently bought a new home with a rectangular pool, 40 ft by 20 ft, estimated 30K gallons. I tested the water chemistry and most numbers are off the chart:

CYA >= 400 (after 1:4 dilution)
TA 225
CH 1525
PH 7.5
FC 12

The pool has been maintained by a pool service company using pucks, and probably the water hasn't been exchanged for a long time, so all the CYA, calcium, etc. have been accumulated in the water. Surprisingly the water is very clear, and the pool service guy said this pool didn't have any algae problem in the last 3 years. I'd like to replace the water, but cannot decide whether to do it now or wait till Nov/Dec. Here're the considerations:

- We're in Tucson, it still gets to 100 degrees during the day. Draining the pool would risk plaster damage.
- There're some dark area at the bottom of the pool (see picture). I was told they're dirt on the plaster and can only be cleaned after the pool has been drained. If so, cannot do it until the weather cools down.
- If not draining now, I have to maintain FC at a high level (> 10), which I think will damage the pool cover's brand new fabric for a few months.
- Also if somehow algae gets a foot hold in the pool it'll be impossible to SLAM it.

What would you experts suggest in this situation?

Also, the pool has in-ground cleaning system. It doesn't seem to be very effective from my observation. I've purchased an Active 20 robot from Marina to do the cleaning. Can I somehow turn off the in-ground system? so to make the water circulation better, I guess?

Thanks in advance!

 

[Texas Splash]

What would you experts suggest in this situation?

I would wait. Give the temps a bit more time to fall so the intense sun doesn't blast the exposed plaster. Once empty, examine that stain closely and do some testing. It might be copper if the previous owners or company used copper-based products.

 

[TexEdmond]

Can I somehow turn off the in-ground system? so to make the water circulation better, I guess?

I've been wondering the same about my system. How familiar are you with the individual pipes going to and from the pool? It's possible you might have a bypass already plumbed in. My pool definitely doesn't, I'd have to add that on my own by hooking up the nonfunctioning port in my deep end.

I didn't try it (and you probably shouldn't either) but I had a thought taking the lid off the in-floor cleaning system and physically removing the valves and orbital gear from the pool pipes would probably do the trick.... but again, that's just my crazy idea and it'd probably blow something up somewhere else.

I have to maintain FC at a high level (> 10)

If your CYA is actually 400, you're going to have to maintain an astronomical level of FC in order for it to even be safe to swim in your pool.

If you notice in the FC/CYA Levels chart, you'd actually need 32ppm FC at minimum to safely sanitize the water in your pool. There may be so many metals dissolved that algae won't grow, but metals do not kill bacteria and virus. You are correct to notice that if algae does find its way in, you're in a very bad position and would need to drain refill anyway.

If fill water isn't an issue, I'd see if there's a way to set your pool pump to drain starting just at the time your pool is out of direct sunlight and it's started to cool off for the evening. What I did with mine (mostly just because I'm a night-owl, not for the heat consideration) I drained my pool down to a certain level, then stretched a hose from all 3 of my hose bibs on the property and let them run overnight to refill. If you calculated it correctly, that'd be one way to do things. Or there is a tarp method some folks have gotten good use out of, basically using a tarp to create a barrier so new water doesn't mix in as much while draining from the other side of the pool.

If it's 2 months and you still want to swim in the pool, I'd say diluting your water down ASAP is the correct action. It probably isn't safe to swim in your pool because your high CYA might be keeping you from actually sanitizing the water against pathogens. Algae is harmless; norovirus and cryptosporidium aren't.

What would you experts suggest in this situation?

EDIT: I'm not an expert. Please disregard my unqualified opinion if you care to.

 

[FS2019]

I would wait. Give the temps a bit more time to fall so the intense sun doesn't blast the exposed plaster. Once empty, examine that stain closely and do some testing. It might be copper if the previous owners or company used copper-based products.

Ah, good point, I didn't think of that. since I don't have anything to test metal, I brought to Leslie's for a water test. The result is iron 0.2ppm and copper 0.3ppm, phosphate 3742. I'm reading the forum about pool stain and plan to use the trichlor/VC/dry acid method to test what kind of stain it may be.

 

[FS2019]

I've been wondering the same about my system. How familiar are you with the individual pipes going to and from the pool? It's possible you might have a bypass already plumbed in. My pool definitely doesn't, I'd have to add that on my own by hooking up the nonfunctioning port in my deep end.

I'm attaching a picture of the pool equipment pad. Is the valve adjacent to the in-ground thing (at the bottom left corner of the picture) a bypass?

If fill water isn't an issue, I'd see if there's a way to set your pool pump to drain starting just at the time your pool is out of direct sunlight and it's started to cool off for the evening. What I did with mine (mostly just because I'm a night-owl, not for the heat consideration) I drained my pool down to a certain level, then stretched a hose from all 3 of my hose bibs on the property and let them run overnight to refill. If you calculated it correctly, that'd be one way to do things. Or there is a tarp method some folks have gotten good use out of, basically using a tarp to create a barrier so new water doesn't mix in as much while draining from the other side of the pool.

If it's 2 months and you still want to swim in the pool, I'd say diluting your water down ASAP is the correct action. It probably isn't safe to swim in your pool because your high CYA might be keeping you from actually sanitizing the water against pathogens. Algae is harmless; norovirus and cryptosporidium aren't.

So I'm reading the forum on the tarp method. One question: it seems the potential issues of tarp method mostly come from the fact that the pool is being drained and filled at the same time to protect vinyl. Since my pool is plaster and the main concern is the sun, can I just drain under the tarp cover, and after that fill the pool? The temperature is still in high 90s, but the pool surface will not be under direct sun light during this process. Could this be a way to use tarp method without most of its potential pitfalls?

 

[Texas Splash]

That is a 3-way valve down on the left bottom. If works like the image below, so you can adjust it as you like depending on where you want water to flow. Your iron and copper levels are right at the threshold where we see problems. The copper is of upmost concern because for that you have to change water which I know you are working on anyway. If you use no copper products later, you should never have that problem again unless it's coming from the heater element (if it's copper). Something to consider looking at.

 

[TexEdmond]

Thanks for sharing the equipment photo. Do you have a spa?

On the left side my first guess is that valve lets you select spa vs pool on filtered water returning from the heater. If you don't have a spa, that valve would almost certainly be your bypass, given the floor cleaner curator valve right there. On the right which is your suction side, it looks like there's a valve that should let you select between skimmer and floor drain, or it may be pool return / spa drain. What interests me is the capped off pipe on that side. That may have been a suction return for a pool robot perhaps? Do you have any ports in the side of the pool that don't seem to do anything?

The other pump, does that just drive waterfall / fountains / features? Looks to be a completely separate plumbed system.

 

[FS2019]

That is a 3-way valve down on the left bottom. If works like the image below, so you can adjust it as you like depending on where you want water to flow.

Yes. The valve controls the return water between the in-ground system and the return jets on the wall. Thanks!

Your iron and copper levels are right at the threshold where we see problems. The copper is of upmost concern because for that you have to change water which I know you are working on anyway. If you use no copper products later, you should never have that problem again unless it's coming from the heater element (if it's copper). Something to consider looking at.

I do have a heater, will need to look into it later. It appears to have a bypass valve as well, which should make things easier.

 

[FS2019]

Thanks for sharing the equipment photo. Do you have a spa?

On the left side my first guess is that valve lets you select spa vs pool on filtered water returning from the heater. If you don't have a spa, that valve would almost certainly be your bypass, given the floor cleaner curator valve right there.

I don't have spa, and you're right, it is the bypass I'm looking for.

On the right which is your suction side, it looks like there's a valve that should let you select between skimmer and floor drain, or it may be pool return / spa drain.

I just verified this valve is for skimmer vs. main drain.

What interests me is the capped off pipe on that side. That may have been a suction return for a pool robot perhaps? Do you have any ports in the side of the pool that don't seem to do anything?

Not sure which part you're referring to, I don't see any capped off pipe. But I do have a couple of ports on the side of the pool that don't seem to have any water flow and I have no idea what they're for.

The other pump, does that just drive waterfall / fountains / features? Looks to be a completely separate plumbed system.

It's for solar heating coils on the roof. The controller doesn't seem to work, but I'll deal with it later after dealing with the plaster stain and water exchange.

Thanks!

 

[TexEdmond]

That's great. Good sleuthing.

One thing I notice about your heater plumbing: it looks like that ball valve is basically just a pressure bleed valve if your pump was to exceed the max flow rate of the heater. It's not uncommon to see those on heater and SWG install manuals. You'd need a check valve or other plumbing after the heater for it to be a true bypass. Assuming it's been closed a long time it might not be a bad idea to just leave that heater ball valve closed.

The great news is, you've got plenty of room to upgrade to a true heater bypass and that salt water chlorine generator you've always wanted...

It's not a big deal anymore since you've found your solution. I drew an arrow to what looks like a stubbed out pipe that's been sealed off.