My local Thin Bleach is <5% Sodium Hydroxide is that OK?

[Langy3366]

Hi,
I read a lot about using Sodium Hydrochlorite and that this is contained in cheap Thin Value Bleach, but my local supermarket Thin Bleach is <5% Sodium Hydroxide, is this OK to use?

 

[duraleigh]

Sure. Just calculate your dosage using 5% instead of the normal 6% found in Clorox.

 

[Bama Rambler]

While it's ok to use, it takes more of it to get the same effect and unless it's very cheap it's usually not a good deal. If you can post the cost, qty, strength and your location someone can tell you if it's a good deal.

 

[Langy3366]

thanks.
14pence per litre (10 cents?)
<5% could be anything close to zero I guess
It also says it has stabilizers too... is that the dreaded CYA I'm trying stay clear of?

For the UK guys I'm talking about Sainsbury's Basic Thin Bleach

ed. maybe caustic soda? NaOH

 

[257WbyMag]

thanks.
14pence per litre (10 cents?)
<5% could be anything close to zero I guess
It also says it has stabilizers too... is that the dreaded CYA I'm trying stay clear of?

For the UK guys I'm talking about Sainsbury's Basic Thin Bleach

ed. maybe caustic soda? NaOH

I doubt that the stabilizers that are referred to are stabilizers in the swimming pool sense (CYA). It's probably more likely that these are things such as sodium hydroxide that are used to adjust pH in the final product.

 

[Bama Rambler]

I gotta stop reading these threads before coffee in the morning.

Butterfly just asked me to look at this again. I missed that you typed Sodium Hydroxide and not Sodium Hypochlorite when referencing the percentage.

I looked online for that particular item and all I could find was for Sodium Hypochlorite so we need to know if Hydroxide was a typo or that's what's really on the bottle?

I'd shy away from it anyway if it has stabilizers in it, even though that's not Cyanuric Acid (CYA) they're talking about, unless you can find out exactly what they're calling stabilizers.

 

[Langy3366]

here's a photo. The pool started to get a green floor this morning so I've upped the FC to 10ppm. It took 12 litres of this stuff to get from 1.4 to 10.4ppm.

I think I understand your question... it looks like it's Hydroxide (with the water) and Chlorite without. so it's less than 5% Sodium Hypochlorite, NOT sodium hydroxide.

 

[Bama Rambler]

Good, It does say Sodium Hypochlorite. All bleach contains some sodium hydroxide so that's not an issue. Your labeling requirements over there probably requires that on the label.

Since it was turning green you're going to have to shock the pool. I can't run the calculation on the bleach because organics were consuming it as soon as you were pouring it in.

Can you proivide us with a complete of test results and how you got them?
pH
FC
CC
TA
CH
CYA

 

[duraleigh]

Well, I overlooked the "<" sign so I guess we need to know how much less.

 

[chem geek]

Sodium hydroxide is kept in bleach to raise it's pH higher than it would otherwise be and this tends to stabilize it in terms of having it last longer (not to be confused with cyanuric acid which stabilizes in a completely different way). I believe the safety data sheet for this "Thin Bleach" product is here. It says that the pH is typically around 12.0 and they used a typical concentration for the sodium hypochlorite of 4% in their relative density calculation.

So while this is reasonable to use, you should measure the actual rise in Free Chlorine (FC) in your pool and not count on this product being a specific concentration.

 

[Langy3366]

pH = 7.4
FC = 10ppm
CC = 1ppm
TA = 178
CH = dont know
CYA = 60

I use a Palintest kit
I know the TA is high and that bringing the PH down to 7.1 and aerate back up will reduce TA. But not sure what to do first.
It's a light skimming of green algae that's 24 hours old max, sitting on the floor of the pool.
I can see the bottom still (4ft)

 

[Bama Rambler]

The first thing to do is get rid of the algae. Don't worry about anything else until you've done that.

With a CYA of 60ppm you need to shock at 18ppm. You need to add 3.5 L of the bleach you have and test and add more after an hour. You need to do that every hour to begin with.
I guessed at the bleach being 4% and your pool being a touch over 18,000 litres to come up with that amount.

If you don't already know, now's the time to learn to use the Pool Calculator. It'll do metric measurements too.

Don't worry about your TA. It will come down as you adjust the pH down until it finds a happy place.

 

[Langy3366]

OK done. It's dark outside now so will be difficult to check till morning.

 

[Bama Rambler]

It's ok to wait till morning. Just test and bring it back to shock level in the morning.

 

[Langy3366]

quick update.
I woke up this morning (no it isnt a blues song)... and added 4 litres onto a FC of 11ppm
My wonderful wife added 2 litres at lunch time whilst I was at work
Reading this evening was 13.6ppm FC and 1.2CC
Swept the floor and sides to stir it up and just added another 2 litres of bleach
The algae certainly looks less shiny green, more browny in color (maybe some sort of decay is happenning)
Just checked ph and it's up at 7.8 so added dry acid to reduce back to 7.4

 

[Bama Rambler]

Looks like you're making progress. Be careful adjusting pH with the FC above 10ppm. Your pH test is likely affected by the high FC.

 

[Langy3366]

1 hour later
15.4ppm FC, 0.8 CC, PH 7.5
Added another 2 litres
going to leave till morning now with pump running.

 

[Langy3366]

Added 2 litres am and 2 litres pm Saturday
Sunday am (14.6ppm and .8ppm). Backwashed filter (very green). Pool dull but not green or cloudy. Can see bottom fine.
Going to consider I'm at the last stage. Maintain Shock today and scrub. Will test tonight and tomorrow for slight FC change.
Temp at moment over here in UK is 41F night, 64F during day so I guess I'll only have a few more weeks left before my little 6kw electric heater gets too expensive to run to maintain a realistic swimming temp.

thanks to all the help I've been given... I nearly packed it all up for winter.

 

[Bama Rambler]

Glad you've made progress and holding shock today and running the OCLT tonight is a good plan.

 

[SJSwimmer]

Though I'm away from home, it REALLY seems like all those Clorox containers say something like "<6%" as well, possibly because if it degrades over time that's all they can guarantee?

That, and you could dilute carefully and test- kit to measure the strength.