1. What is the best way to clean and prepare my BOD bottles?
All bottles and glassware to be used in the BOD5 tests should be prepared as follows:
- Washing Procedure –
- Allow the bottles to soak for 1 hour in HOT soapy water. We suggest Alconox.
- Scrub the bottles with a bottle brush designated for BOD5 bottles only.
- Triple rinse the bottles with hot tap water or rinse until water is clear of suds.
- Triple rinse with DI water
- Acid Wash –
- Allow the bottles to soak in a 10% acid solution for at least 1 hour
- You can use Nitric acid, Sulfuric acid or Hydrochloric acid
- Triple rinse with DI water
HINT: One large environmental lab that has been using PolySeed for 15+ years adds ~ 5 – 10 ml of 1:1 HCL in each bottle, fills the bottle to top with DI water, spot checks bottles to make sure the pH is < 2.0, and store them for up to one week or until ready to use.
2. Can I rinse my BOD bottles with a chlorine (clorox) solution and get consistent results?
No. Clorox is an alkaline form of chlorine (HOCl). Many labs use this process, however, it is not recommended. A very small amount of residual chlorine can cause significant fluctuations in the BOD5 test.
3. Can I use a regular dishwasher to was my BOD bottles?
No. If you use a dishwasher, make sure it is manufactured for BOD5 bottles. We do not recommend washing your BOD5 bottles in a regular (kitchen) dishwasher. The neck of your BOD5 bottle is too small to allow the water circulated by the dishwasher to consistently wash and rinse the interior of the bottle. If you were to set up tests in triplicate, you could experience one bottle within the expected range, one possibly too high and the other very low.
4. Can soap residue cause problems?
Yes. Soap residue inhibits microbial action. Thus, the bacteria will not eat, breathe, and reproduce as much, causing low depletions.
5. How do I clean my tubing and aeration stones?
Keep your tubing and your aeration stones (or whatever you are using to aerate the solution) as clean as possible. When finished aerating your solution, pull out the tubing and let the air pump blow out any additional air. Wipe the outside of the tubing with a paper towel.
6. How often should I replace my tubing and aeration stones?
We suggest you replace your tubing once a month and aeration stones once a week. However, this depends on how often you are running BOD’s.
7. What is the best way to clean my glassware (beakers, flasks, pipettes, and pipette tips)?
Washing Procedure –
- Allow your glassware to soak for 1 hour in HOT soapy water. We suggest you use Alconox.
- Wash all glassware
- Triple rinse with hot tap water or rinse until water is clear of suds
- Triple rinse with DI water