To drain or not to drain???

[Algae Hater]

I have been having difficulty maintaining a proper chlorine level in my pool this whole summer (has actually been an ongoing issue since 2017 but much worse this year even though I purchased a new pump and filter system last summer, and this pool has been partially drained twice since 2017 because of high CYA levels and is why I rarely use pucks). I did go to the pool store about 2 months ago and they told me that I had nitrates in my pool and it would have to be drained, rinsed and drained again. Suspicious, I ignored that but kept shocking the pool with just Cal-Hypo every week to sometimes every few days (approx. 16oz each time) but never could maintain a FC above 0.5, didn't use tabs since my CYA was in the 80 range. I went through an entire 25lbs of Cal-Hypo in a little over a month. Bought another and was told my CYA was down to 60 so added a puck to the feeder to try and keep some chlorine in the pool between shocks.

I just got back from being away for about 4 weeks and while the pool was maintained by a friend by shocking it weekly with Cal-Hypo (approx. 20 oz) per week and keeping a couple tri-chlor tabs in the feeder set low, and brushing, I now have what looks like mustard algae on sides and steps that can't be brushed away. So yesterday during the day I added about 24 oz of Cal-Hypo since the pool was at about 0.5 FC and a pH of 8.0. I knew it would take a lot of chlorine to kill whatever can't be brushed away. Then last night I added 10 oz of muriatic acid and waited an hour to then added 4 gal of 10% liquid chlorine. I did not do a DPD test as I determined I was going to need a lot more liquid chlorine than that 4 gal, but thought the chlorine level would still be high by the next morning.

This morning the FC is down to 2.5 according to the DPD and the Taylor K-1004 test showed 1.0. Seems like an awfully drastic drop in Cl overnight. So I'm wondering if I should just drain the 13,000 gal pool since it only costs like $150 to fill it and I'm spending way more than that chasing a Cl level. I did pick up 6 more gal of 10% Liq Cl for use tonight but don't want to use it if I'm just going to end up draining the pool.

As of 1040 this morning my levels are:
2.5 FC (DPD test), 1.0 (K-1004 test)
0.5 CC (DPD test), 0.5 (K-1004 test)
1.5 TC (K-1004 test)
7.5 pH (so the 10 oz of muriatic did work)
45 CYA
120 Alk
86 degrees F

I don't have a calcium hardness test but like to keep it high since this is a plaster pool.

 

[DorsalSpine]

If you can safely drain and clean the pool for $150 I'd consider it. You get to start with new water and you can follow TFP from the start.

 

[Texas Splash]

Hello neighbor and welcome to TFP! By the way ... it's HOT! So, I'll add a few more things:
- The K-1004 is fine for pH and TA, but that appears to be about it. You really need the TF-100 which also has the CH test, CYA, and the FAS-DPD which will give you the accuracy and ability to test FC at much higher levels. The TF-100 is a must.
- You can ignore any discussion about nitrates. Alge requires a SLAM Process. Drain, fill, and drain again? Good you walked away.
- You appear to have a bit of Mustard Algae along those benches.
- A large water exchange may be beneficial, however I would be curious to know what your CH and CYA levels are first. Based on all the shock bombs you did, they may be quite elevated, but it's always good to know beforehand.

Whether your drain or treat the current water, you should order the TF-100 and read the SLAM Process page so that you can treat any residual algae. Give it some thought and let us know if you have any other questions.

 

[Algae Hater]

Thanks for the info. The K-1004 results were basically verified or vice versa by the DPD-FAS test I did. We have very hard water down here in South Texas so the CH would be naturally high, always has been. I purposely use a spigot not connected to the water softener system to fill because I have a plaster pool. CYA is a manageable 45.

Speaking with my friends up in NNY, they too have been having unusual Cl demand issues and pH levels with their pools this year. Like nothing they've ever had to deal with in the past.

 

[Algae Hater]

So I'm draining the pool. I'm also attempting to power wash the areas that looked like mustard algae but the power washer (2000 psi) is not removing the areas on the steps that had heavy growth (see original pics). Should I fill before getting those spots removed? Or should I scrub with muriatic acid or something?

 

[zea3]

Get a pair of rubber gloves to protect your hands and just rub the stain with a damp puck. Wear something you don't care about as it will get bleached.

 

[Algae Hater]

I will try and post results. Tried a steel brush that seems to work as well. Just want to be careful not to scrub too hard. Thanks for the advice.

 

[Algae Hater]

Using a wet puck worked well on stubborn areas that powers washing wasn't taking off. Found a pair of NBC gloves from my Army days. I knew I saved those for a reason. Looks much better now. Thanks for that advice.

Now I'm wondering if I should get it resurfaced or just wait until the fall or winter. It was last resurfaced 10 years ago. No the power washer did not do that, surface looked like that before only with algae.

 

[zea3]

If y'all are expecting a bunch of rain from the incoming tropical system you will want the pool full so it doesn't float from a high water table. I'd go ahead and refill and wait til winter to resurface. I don't know if you could find someone available to do it now anyway. Pool builders are extra busy this year.

 

[Oly]

If it does not leak, I agree fill it and plan the resurface next season. I actually kinda like the look of the textured (distressed), multi colored plaster.

 

[Algae Hater]

Thanks. Fill I will. It's HOT!!! here and I don't know if I can stand not having a dip this weekend. I am going to look at that aqua bright product for the future.

 

[Oly]

Post some before and after pics when it's full.

 

[Algae Hater]

Looks better now and even better to swim in. My CYA is really low for the first time since owning the house (less than 20ppm). So I put a couple pucks in the feeder to get that to come up. There was a layer of like half an inch thick gelatinous dark green sludge behind the pool light, so maybe that was what was eating up all my Cl and causing such a high Cl demand? We'll see if I can keep the FC at 4 once my CYA comes up.

 

[Texas Splash]

There was a layer of like half an inch thick gelatinous dark green sludge behind the pool light, so maybe that was what was eating up all my Cl and causing such a high Cl demand?

Good catch! Getting there.

 

[Algae Hater]

It's been a couple of weeks since I drained, cleaned and refilled. The water looks great and I'm testing it all the time. I've been chasing my pH since refilling and having to add a lot of muriatic acid to get a starting TA of 230 down. I finally received my CH test today so I did a few tests to see what's going on.
Pool water currently tests at FC 2.0, TC 2.0, pH 8.2, TA 130, CYA < 20, CH 160, 86 deg F.

I was surprised to see that the CH was so low. So I tested the pool spigot (supposed to be not connected to water softener) to see what I started with, and another yard spigot.

I only tested for CH and TA on the pool spigot which came to CH 220, TA 200. Other spigot is definitely connected to water softener as it was a CH 10 or 20.

Because I was trying to maintain a FC of 3 and saw that the CH was low so I added 4 oz of Cal Hypo. I've also have been running my tri-chlor tab feeder all the way open with a couple pucks at a time to raise the CYA. Keeping a level FC has been difficult as well and I've been adding 10% Liq Cl every day, usually around 42 oz.

CYA doesn't seem to be raising much and I'm adding acid everyday but slowly as I'm fearful of messing up the pool surface (have added nearly 180 oz of muriatic acid over a 11day period) . The water is clear and looks great. Should I be chasing my pH and continue to keep adding acid? It has brought my TA down to 130. Will continuing to add acid affect my CH? I thought of switching to Cal-Hypo until my CH comes up but then it supposedly raises TA as well. Any suggestions on how to proceed?

Maybe I should just manage my FC and not worry about the pH and TA?

 

[zea3]

You do need to be concerned about CH levels with a plaster pool. Using cal-hypo will not raise the pH, but it won't add the calcium you need quickly enough. 1lb of 73% cal-hypo will add only 4.7 ppm of calcium and 6.7 ppm of chlorine. You have several testing parameters to correct sooner rather than later.

1. Get the pH down in the 7.2-7.8 range. 8.2 is the upper limit of the test. Your pH may be much higher. Use muriatic acid to drop the pH. Test and dose the pool in 30 minute cycles with the pump running until you get the pH down. This is not something you can do once a day or once a week and get it under control when it is so high.
2. Get the CYA up to 30 ppm at minimum. Buy some granular CYA and put it in a clean white sock, tie off the sock and put it in the skimmer so it doesn't block the flow of water into the pump. You can have the CYA sock in the skimmer while you are dropping the pH.
3. Add 12 lbs of calcium chloride or 16 lbs of calcium chloride dihydrate to raise the CH to 260. This is the minimum level to protect the plaster finish from premature deterioration.

Once the CYA level is 30ppm be sure to adjust your target FC level to stay in the correct ratio. Your new target range is 4-6 and you should never allow the FC drop below 4 ppm.

 

[Algae Hater]

I added 16 oz of Muriatic Acid this morning and it dropped the pH to 7.7 with an FC 1.0. And I added 6 oz of Cal Hypo tonight. I will pick up some granular CYA and calcium chloride tomorrow, and try the sock method. I'm out of liq Cl so I'll pick up some of that too, but it seems to push my pH up every time I use it. pH has been a constant struggle since buying the house in 2017.

 

[Algae Hater]

Pool math shows my CSI as okay.