Finally used my new test kit and have a couple questions

[motv8r]

First, I'd like to say this forum has been awesome! I've learned a lot since I started lurking around, and even bought a TF100 test kit!

I have been putting this off for some time now as I've always thought pool maintenance would be very difficult. Fortunately, the tests were pretty straight forward. Now I need to know a few things. Here are my specs and test results...

14,500 IG plaster pool with a DE filter
I think my pump is a 3/4 HP, but don't know the flow of the filter

FC: 8
CC: 1
TC: 9
pH: 7.2
TA: 60
CH: 550
CYA: 100+

According to the pool calculator I need to drain approx 1/2 of my pool and refill. My question is regarding some stubborn algae, both green and black, that I can't seem to get gone. Should I use a muriatic acid wash after I drain the pool, or could I just use my pressure washer instead, or both? Also, if I need to use the acid does it need to be neutralized afterward?

Thank you in advance for any advice!!!

 

[Melt In The Sun]

Hi Motv8r, welcome to TFP!

Sounds like you have been reading and have a good idea of what to do. Unless you have substantial calcium scaling or copper stains, there's no reason to do an acid wash at all. I would avoid it if at all possible, since it will shorten the life of your plaster.

It sounds like you're planning on doing a total drain? Unless you are going to do an acid wash, there's no reason to do that. Where are you located?

 

[dmanb2b]

Welcome to TFP...if the stains are organic (algae), they will go away once you are able to shock your pool. CYA is your culprit at 100+ it is really difficult to shock a pool. Curious...you say 100+ on CYA, have you tried diluting the pool water with bottled water (50/50 mix) and then trying the CYA test? Trying to figure out if you are close to 100 or much higher?....If you are near 100, the 25% pool water 25% bottled water/50 % R-0013 dilution should read around 50 on your test vial

 

[waskydiver]

One suggestion would be to simulate your refill. If you are going for a 1/2 drain, add one part pool water to one part source water, and test the mixture.

Largely, that will let you know how much (+) there is in that 100+ CYA reading. I'm also a tad concerned about the CH reading, and would want to know if your source water will make matters better or worse.

 

[motv8r]

Melt In The Sun,
Thanks for the reply. I would prefer not to acid wash my plaster as it appears to be in need of replacement in the next year or two, so I don't want to hurry the inevitable.

I planned to to drain just over half, which would give me access to the majority of the problem algae. I am located in Fort Worth, TX.

dmanb2b and waskydiver,
I did not try diluting the water, but will this evening. I didn't measure the distance below the "100" line, but I'd say it was 2-3mm below the line, hence the 100+. I'll also try a CH test on my tap water alone, which should give me an idea how much/little the refill will help.

Thanks for the input and the welcome. If anyone else has any other ideas, I'm all ears...

I'll post the results of my next tests this evening.

 

[motv8r]

Ok, I re-tested the CYA & CH tonight. Here are my results...


CYA using 1/2 pool water and 1/2 tap water: 75

CH using tap water only was 140 and using filtered water from the fridge was 130.
I am out of bottled water so these will have to do for now.

Please let me know what you think because I'm thinking I'll need to drain more than half to get things right.

 

[Melt In The Sun]

Sounds like you need to drain about 2/3, assuming your targeted CYA is 50. That would lower your CH to about 300, which is an easily managed level. Once you refill, it'll be time to shock!

How about some pictures of the pool?

 

[motv8r]

Ok, I've decided to drain my pool tonight. I need to know if there is anything I should do while it's empty or any precautions I should take. My plans are to pressure wash the walls to remove the remaining algae, then refill. Are there any other steps I should take? I know this is last minute so thanks for the replies!

Also, I asked about what to soak my DE filter in to give it a thorough cleaning in another forum...sorry for the double post. It holds water even after it's been cleaned.