What is cheapest online source of ascorbic acid?

Any links would be appreciated.
Thanks

Here are tow places I have ordered from:

http://www.msm-msm.com/store/agora.c...scorbic%20Acid
this one is good if you don't want to order much.

This one is good to order larger amounts:
http://www.chemistrystore.com/Ascorbic_Acid.htm

You don't have to order food grade.:)

Thanks Marie,

I need a fair amount since I have to clean a 1000 gallon gunite 'kiddie' pool badly stained with iron.

I would guess the best approach is to drain, partially fill with FC level at 0, get ascorbic acid concentration high and circulate until stains are removed.

Is rubbing with wire brush helpful? Do I need to buffer pH? Is there any risk to the plaster if pH is low for an hour or two?

Thx

Sorry, forgot to ask if i need a sequestrant in there also?
I will be circulating through a hayward filter and I will be draining to waste.

You do need sequesterant in the water if you are filling from the same source. You don't have to drain. All you have to do is to let the chlorine drop down to 0, keep your ph where it is, add the ascorbic acid - I use 1lb to 10,000 gal, so if you meant you have only 1000 gal, then you wouldn't even need a whole lb. This is what I do: Drop chlorine, put pump on circulate, add ascorbic acid. You will be amazed how fast it removes the stain just drop it around the perimeter of the pool - no need to scrub. After all the stain is gone - add sequestering agent according to the directions on the bottle you have. Put the filter back on filter and leave it on for 24/7. You can throw some polyquat algacide in if you are worried about algae. Just keep filtering, and do not shock for at least a week. You can start to add some chlorine after 48 hours. Just use bleach, becuase the ph will go way down from the ascorbic acid - you have to start to bring up the ph after 24 hours. Do not take it higher than 7.4 - it will be hard to hold until all of the ascorbic acid is gone. You will also have to keep a constant check on the chlorine when you start to put it in, because the chlorine is eaten up by the ascorbic acid - so you will not be able to hold chlorine until all the ascorbic acid is gone too. Feel free to ask any other questions:)

Once the ascorbic acid arrived, I followed your instructions. Unfortunately despite a high concentration of ascorbate (1lb in 1000 galloons) and sequestrant and vigorous wire brushing, the brown stains did not completely come off even after 48 hrs of recirculation. Of note there was quite a lot of a brown precipitate on the floor of the pool.
I emptied the pool and applied ascorbic acid powder directly to the brown stains (having dampened them with a sponge). The next morning there were green stains in the treated areas (presumably iron ascorbate) which were removable to some extent by washing with tap water (pH 7), the remainder coming off with a gentle power wash. A quick google failed to reveal the physical characteristics of ferrous/ic ascorbate. There was no damage to the plaster.
The pool surface is now free of iron stains and refilled with iron free water! Thanks for the help:-)

Thanks for following up with your results:) It is how we all learn. Happy swimming!

The steps for Ascorbic Acid indicate that you need to turn your pump on circulate instead of filter. I don't have the option to bypass my filter. I do have a second pump that powers the water features but don't know if that will circulate the pump well enough. Is it a big deal to not use the filter at first when adding ascorbic acid?

You can just leave the pump on filter - it will still work. Good luck:)