brown/tan stains= calcium scale?

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C

caliking

0
May 11, 2012
62
Houston, TX
Hello all.

New member. Apologies if this should go to another section - the description suggested this was the area for discussing stains.
My pool: 20K gallons, plaster/gunnite, DE filter, trichlor.

My numbers from testing at Leslie's:
FC 5
CH 480
CYA 120
TA 60
pH 7.2

I know that Leslie's testing may not be the most accurate. I tested with a strip also (again, not the most accurate) and the results are somewhat consistent.

I also have brownish/light tan stains on the floor of the pool, mostly in the deep end. Occasionally, over the past year ( but more as the weather in TX started to get warmer) I have noticed a light tan film on the plastic/vinyl parts of my Polaris cleaner or the drain covers. The metal rims around the lights used to be shiny, but now are brownish.

I'm not sure whether my problem is calcium scale, organic or metal staining... so I'm even less sure of the solution. The pool calculator suggested draining and refilling my pool 35-40%, as well as adding baking soda to increase TA.

Draining and refilling water is an expensive option. Can I neutralize the chlorine with sodium thiosulphate? Do I need to lower the pH further?

Your recommendations would be most appreciated. Thanks.
 
Aloha caliking!

Good thing you came here and asked!!

Without a photo, it is hard of us to use our experience to help you on the staining issues...so you may want to consider sending a photo if you can--but the first thing that popped into my mind :idea: was iron staining. If your chem levels have typically been as you show in this test, it is probably not calcium scale, as your Calcite Saturation calculates out to a negative number, even with CH of 480. Try to find out what your water source is...is it perhaps stored in a rusty tank for awhile before it heads your way through rusty pipes? :wink:

As for the chemical things:
1) PoolCalculator advised to drain and refill because your CYA is VERY high (not because of the chlorine). The high CYA creates a need for HIGH chlorine levels which is expensive also. If you get lots of rain or cheap municipal water, consider the drain and refill (it will make things SO much easier for you). My customers who have no access to municipal water just "vacuum to waste" and let the daily rain bring the water back up (diluting it every day).

2) You should really NEVER have to use Sodium Thiosulfate to bring down chlorine levels (it decreases fast enough on its own)...and your 5 ppm free chlorine is actually VERY LOW for your CYA level. You need to keep the proper ratio of chlorine to CYA, and in your case (CYA=120 ppm), your FC should be minimum of 8.4 ppm and maximum of 13 ppm (that is just the normal maintenance range for CYA=120 ppm). Find a source of chlorine that doesn't add CYA to your water--liquid chlorine is probably the best choice for your situation. No more 3" tablets or dichlor shock!

Hope this helps!

Aloha!
 
Yes...a partial drain and refill, not a "drain the whole pool" and refill.

The purpose of the partial drain and refill is to reduce the CYA to a workable level, but we don't want to waste money...so we remove enough water and CYA to get to somewhere around 30 ppm CYA. So if we drain out 75% of the water, then refill, the CYA should come out around 30 ppm. At the same time, Calcium Hardness should drop to around 120 ppm, but she may have a lot of calcium in the refill water, so this should be checked. Alkalinity and pH may have to be adjusted too. Once finished, the pool should respond to chlorine real well, and chlorine maintenance and shock levels won't be so expensive! :whoot:

Aloha!
 
I'm not sure whether my problem is calcium scale, organic or metal staining... so I'm even less sure of the solution.
Click to expand...
So, let's identify the stain first. Hold a trichlor puck on the stain for a minute or so, if the stain disappears or lightens noticeably, the stain is organic.

If that doesn't work, crush up 10-20 cheap vitamin C tablets and put them in a sock and then hold them down on the stain for maybe a few minutes. If the stain disappears or lightens considerably, the stain is metal. Post back.
 
Thanks for the info duraleigh, teapot, and BigIslandPoolService! I was planning on doing the trichlor puck test vs. vitamin C this weekend.

Here is a pic I took yesterday (pardon my n00bness, I don't know how to upload images): https://www.dropbox.com/s/ivkf5421eaqoq ... .54.07.jpg

PoolCalculator suggested a 40% drain and refill, so I was thinking of trying that first (vs. draining 75%). I have to replace the light bulbs and light gaskets so maybe I can do that when I drain. Do I need to take any extra precautions when I drain and refill in terms of algae?

Trichlor just went on sale at Costco ($80 for 40lbs) and I stocked up with about 400lbs. I guess I will return it and consider liquid chlorine or bleach instead. HTH shock claims it does not raise the free chlorine and I seemed to have had good results when I used it for the 2010 season. Can I use hth shock and bleach in the future, or would it be easier to just use bleach for maintenance and shock?
 
caliking said:
HTH shock claims it does not raise the free chlorine and I seemed to have had good results when I used it for the 2010 season. Can I use hth shock and bleach in the future, or would it be easier to just use bleach for maintenance and shock?
Click to expand...
I think you meant it doesn't raise the CYA. It's probably cal-hypo.
IF it's Cal-Hypo, AND your CH is low you could use it, but you'll have to keep a close eye on the CH to make sure it doesn't get too high.

Bleach is preferred and the best for the pool, but if you already have the cal-hypo and know what it does, you can use it.
 
Aloha Caliking!

Still hard to tell with that photo through the surface...but it looks consistent with iron staining...your testing this weekend will confirm one way or the other. If it proves to be staining, MAKE SURE you study the existing info on stain removal in the Pool School. It can be a difficult process sometimes, and the experience of others might really help you to avoid a mistake.

When I entered CYA of 120 in the PoolCalculator.com, it suggested 75% drain and refill (that's with a GOAL of 30 ppm). If you do a 40% drain, you will simply find that your CYA is still too high. If you aim to do a stain removal process, you'll need to deplete your chlorine, and that can take a LONG time if your CYA is at 120.

Take those TriChlor tablets back to HD (it's good to have a small amount on hand for using in a floating dispenser when you go on a trip) and use the money to rent a fast trash pump there...costs me less than $40 at my HD, and it will pump out 75% of your pool in about 90 minutes! Then do your refill, add baking soda and other chems as needed. Now bask in the ease of keeping your CYA between 30 and 50 ppm. If it is down at 30 ppm, you can use a bag of dichlor based shock every once in a while, and if it gets up above 40 ppm, use the liquid bleach so it doesn't rise.

Buy yourself 4 gallons of quality 6% bleach (this means FRESH--so don't buy too much at a time--and never store it in the sun!), I've found the HD Clorox and WallyWorldGreatValue to always be good. This stuff will serve as both your daily maintenance AND your shock, with no down side like some of the other forms of chlorine have.

Use the Pool School, use your new friends here...and persevere...

Aloha!
 
Thanks all for your helpful tips.

It sounds like the first order of business should be the drain and refill. I will try to do this tomorrow, and also do the vitamin C tablet test. Once I have the pool refilled I will work getting the water balanced re: other parameters. I like the idea of using regular bleach to maintain and shock the pool especially if it keeps the CYA down.

Thanks again.
 

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caliking said:
It sounds like the first order of business should be the drain and refill
Click to expand...
If your cya number is correct then you are right and a drain/refill is appropriate. You may have read on other threads where we stress the need for a good test kit, and so do you (see my sig)! It will save you money and time in the long run. You/we do not know that the pool stores number is correct as this of all tests seems to be botched more often then not by pool stores. However, since it sounds like you were a trichlor user (were you?), it is likely high.

caliking said:
I like the idea of using regular bleach to maintain and shock the pool especially if it keeps the CYA down.
Click to expand...
This and saltwater chlorine generators (swg) are our preferred approaches to chlorinating a pool since they add nothing but chlorine (and salt) to the pool. Regular bleach or liquid chlorine are good choices.
 
Beez said:
Is that a photo of a wall or the floor of the pool? The pattern looks like calcium scaling to me.
Click to expand...

It is a pic of the floor, taken from above the surface of the water.

I tried to drain my pool in the evening, but cannot seem to drain it more than several inches. Off to HD in the morning to see if I can rent a pump. Will be busy tomorrow with the pool.

I'm thinking my trichlor days are over. Have to lug the 400lbs back to Costco sometime this week. Guess I can pick up some bleach when I'm there!

I do realize the value of a good test kit, and that will likely be my next investment. Even if Leslie's testing was accurate, it is a PITA to drive over there every time I need to get my water tested, especially with the close monitoring I will need for the next couple of days to weeks.


Thanks everyone for the help. I really appreciate it. Will keep you posted about how things progress.
 
Went to HD and got a submersible pump. Hooked up the hoses and draining the pool as we speak. Stocked up on bleach from WalMart. Will plan to refill overnight and see what things are like tomorrow. About to go do the vit C vs trichlor puck test on the stains.
 
OK - the stains seem to get lighter when rubbed with vit C tabs, so it must be iron then? Any recommendations for where to buy ascorbic acid?

I just had another thought - it rained like crazy on Fri night, several inches probably. Am I in danger of floating my pool since the groundwater level may be high now? I was planning on draining about 70% of the water.
 
Aloha caliking! :wave:

Chlorinate now, while the water volume is lower! That will necessitate less chlorine to reach a good shock value. Now you can make adjustments and your chemistry will be good! But give it some more time before you tackle the stain problem...or you might find that your blue gunite actually gets its colore from metals, and loses color due to the acid you add.

By the way, you don't HAVE to use Ascorbic Acid if it is difficult to get or too expensive where you are. Citric Acid also works (you have to use a bit more...see the info in Pool School). The stain removal process is something you need to go over several times in your head, and you need to have the time to watch it carefully for a couple of days at least. Algae can go nuts pretty quickly if it is warm there, and you can't shock with chlorine once you've "pulled" the stain into the water (high pH and chlorine tend to make it precipitate right back in to your plaster). :grrrr:

Do you have a remover to get rid of the metal once it is suspended in the water? Or were you planning to just keep it sequestered for eternity (a high standard for ANYONE to meet). Study before you just jump in!

Aloha!
 
Thanks for the ongoing recs, BigIsland.

I'm trying to learn as fast as I can! But the learning curve is pretty huge in my case. I have ordered my TF 100 test kit, but it will take a couple of days to arrive. Will have to make do with Leslie's and my cheapo test kit until then. The last 2-3 days have been spent reading up as much as I can, and I have learned alot from the helpful members on here.

Pool filled overnight. I poured in the amount of bleach recommended by the pool calculator. Thanks for the tip about WalMart brand bleach. Ascorbic acid was a reasonable price on Amazon, but I might wait a bit before tackling the stains.

I admit I jumped the gun a bit, by not having all my ducks in a row before embarking on draining the pool and refilling. I should have had the metal sequestrant on hand, but I will see if I can find it locally - was going to try Jack's Magic Pink Stuff. I would have also preferred to have poyquat 60 on hand also, but what is done is done. This will teach me to be better prepared in the future.
 
Not to worry Caliking...you're doing fine!

The drain/refill operation was only to lower your CYA, and you've got that done now...so you should take a breather now and just get your pool balanced chemically. The lower CYA will allow you to use a normal amount of chlorine to maintain and shock, and will also enable you to drop your chlorine level to 0 ppm when the time comes to do the stain treatment. Meanwhile, get all your ducks in a row as far as needed chems and stuff (Polyquat 60, Ascorbic Acid, sequestrant, and CuLator bags). Don't start until your are REALLY ready...or you will learn a hard lesson from your impatience. Take it from someone who's been there.

When you begin, it should go something like this:
1) Everything balanced, pool looking good. Free chlorine level at bottom of acceptable range (about 2 ppm FC if your CYA is 30 ppm)
2)Add enough Polyquat 60 to keep the algae at bay when there is no chlorine present.
3) Stop addition of chlorine so your chlorine will start dropping (from sun and oxidation of stuff in the pool)
This is where you might have a break of a day or two...
4) When the chlorine is down to 0 ppm, you can begin the Ascorbic Acid treatment according to the directions in the thread on that.
5) Keep in mind that some iron stains will be "treated" but still sit there until you brush them (nylon brush works fine--they will brush right into solution).
6) Use the brush before you decide that you need more acid...use the least amount that will get the job done, as it CAN remove top-layer plaster coloring
7) When the stains are off the plaster (into solution), add your Sequestrant according to directions.
8) Put the CuLator bag(s) in the skimmer and keep that pump running baby!
9) CuLator bags can stay in for a month if needed. If you have iron in your water, it will be smart to use them for prevention!
10) Also remember not to shock until your metal is out, and keep the pH in the lower range (7.0 to 7.3--avoid 7.8 or above!)

That's pretty much it...according to my "senior moment" brain, anyway...other members please correct if you see I've missed anything!

Aloha!
 

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