2:1 sugar syrup-preventing fermentation

[challenger]

I am scorring big time on sugar syrup from American Refining in Charlotte,NC. They sell 2:1 (67% solids) for $7.00/5 gallon bucket if you provide the bucket. I am 4 hours from there but I have someone coming my way that lives there & is getting me 25 gallons. When I mix my own 2:1 syrup I boil the water before adding the sugar and I dissolve 20 grams of vitamin C plus I put in 3/4 tablespoon of household bleach. Even with this I can smell some odor of fermentation if it isn't used within about a week. Is there anything I can do to keep this syrup from fermenting short of refrigeration?I am planning on filling com by& putting the comb directly in the hive. I am pressed for time &would like to wait a week prior to filling the drawn comb. Ideas are greatly appreciated.

Thanks Howard

[RAK]

I add Pro health (HBH) into all my syrup and it never ferments. I have made invert syrup without HBH and it sat for a year and did not ferment. Had to make 300 gal this fall.

[BEES4U]

Check the bleach %
Some bleach is 3.0% and the stronger ones are 6.0%
Good luck.

[cdevier]

When I mix up sugar water, I add a teaspoon or 2 of Pro-Health (MannLake) and a teaspoon of lemon juice to each gallon (helps drop the PH to about 5). Been doing this for a year and a half and hardly any mold, mildue or fermenation. The instructions are to add 4 teaspoons per gallon, but I only use it to get the bees to eat more. I believe that during the dought this summer that the oils caused more robbing; so I went back to just sugar water.

[challenger]

I have several jars of DIY HBH. I made it a few years ago and froze it. I thaw it as needed but I too found it increases robbing which has been at an all time worst this year so I am not using it. I can understand the attraction. It smells so good I imagine it is irresistible to
the bees.
I know they make the syrup with boiled water so I will add 3/4 tablespoon of 5% bleach to 5gallons and it should be good. Forgot to add that putting plastic film on top of the syrup in the bucket is supposed to help keep spores that are iinbetween the top of the bucket &the syrup is also supposed to help
Thanks
Howard