Oxalic Acid question for you chemist forumites

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cliffb

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Having just used a saturated solution in my domestic loo...and been astonished and delighted at the speed and efficacy of the result, I'm wondering just exactly what does it do? E.g. does it lift staining or does it 'bleach' it? And what variety (if that's the right word) of deposit does it work on.
One reason I'm particularly interested in it is because I have a septic tank... and I'm wary about killing it (the tank) completely.
Thanks as ever.
 
it's corrosive, and is a class 8 substance when you transport it e..g. hazardous acid.

It eats away at anything such as general organic crud (fats, greases, etc) found in pipework and frees up the blockage. If it ends up in a cesspit, it increases the level of acidity, and the microorganisms the tank die, or are made inactive, if the pH drops to about 4.5 (or when it rises to above 9.0). The most favourable range for bugs to support digestion in a septic tank is between 6.8 to 7.6 (basically neutral to slightly alkaline).

If you chuck a cupful of bicarbonate of soda down a cesspit once a week, it keeps the system tuned up and biologically active, and also reduces the amount of hydrogen sulphide (the "rotten egg" smell).
 
If you live in hard water area you will lend to get limescale deposits in the lavatory bowl. These will tend to absorb other staining material. Anything acid will remove the limescale together with absorbed stains. Limescale removing lavatory cleaners contain acids. Some even contain hydrochloric acid.

Oxalic acid is also particularly good at removing rust stains that may result from iron in the water.

Not so sure about removing fat a grease. Caustic soda is a better bet for that but they are more of a problem in kitchen sink drains I would have thought. but you would not put caustic soda in a septic tank! Fats etc are also undesirable.

I expect sarabande is right about the pH effects on a septic tank etc but not I would have thought a problem with a cesspit. That just gets emptied when full doesn't it.

I think I would be cautious about using oxalic acid but sufficient sodium bicarbonate to neutralise it might solve the problem if there is one.
 
Thanks Vic,
Hard water limescale is not the problem. I live in a soft water area with my own water supply... which, although heavily filtered, PH corrected, and UV treated still retains much peaty turbidity and causes staining.
I've just bought 5kg of Oxalic and only needed a taddy bit for boaty puposes and found that it worked wonders for shifting the peaty stains in the karzey - also in the kettle and kitchen sink. I was just a mite worried that I might do permanant damage to the cesspit..(that works like a septic...but isn't). Now I know about the bicarb, I'm less concerned.
So thanks to you and Sarabande.
PS... my cess has never smelt ...and I empty it somewhere between five and ten years, working on the principle 'if it ain't broke...'etc
 
Id hesitate to use oxalic acid in the kettle as its quite toxic, I'd keep it out of the kitchen and think you would be better off getting hold of some sulphamic acid which is used extensively as a descaler and yet is reasonably non hazardous
 
As I recall sulphamic acid is nasty in the lungs. Problem with using it to remove lime scale is that you get a lot of effervescence 9frothing) and that might give you an aerosol of sulphamic acid.
I have recently bought 5 kilograms of citric acid for removing lime scale in my heads. I'm less worried about the aerosol here as citric acid is a component of most fruit drinks.
The 5 kg. cost about 18 pounds delivered so its not expensive. I wont know till the summer's over if it works.
 
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