FAQs

Preparation and Use: PolySeed NX ®

Product Information
1. What is the shelf life of PolySeed NX?
2. What material is the PolySeed NX capsule made of?
3. How should PolySeed NX be stored?
4. How many individual tests can one capsule of PolySeed NX perform?
5. Are there any nitrifying organisms in PolySeed NX?
6. Is the chemical inhibitor (Allylthiourea i.e. ATU) used in PolySeed NX approved for use by Standard Methods?

PolySeed Preparation and Use
7. How do I rehydrate PolySeed NX?
8. What do I add the contents of the PolySeed NX capsule to?
9. Can I use deionized water to prepare my PolySeed NX solution?
10. When preparing the PolySeed NX solution, can I just drop the capsule in the dilution water?
11. Should I start my test over if a piece of PolySeed NX capsule falls into the dilution water?
12. If bran is introduced into the BOD bottle will it adversely affect the 5-day dissolved oxygen uptake rate?
13. How long is the prepared PolySeed NX solution good for?
14. What dilutions should I use when performing the test?
15. What type of BOD bottles should I use?

Test Results: Getting the Results You Want
16. What should the DO depletion be for the largest volume of PolySeed NX solution (25 mls)?
17. Is the 5-day Dissolved Oxygen Uptake associated with the microbes or the bran?
18. Why is it common for the GGA standard to fail low when running a CBOD?

19. What should I do if I get High SCF and High GGA results?
20. What should I do if I get High SCF and low GGA results?
21. What should I do if I get low SCF and High GGA results?
22. What should I do if I get low SCF and low GGA results?
23. What should I do if my SCF results fall within the correct range but my GGA results are too high?
24. What should I do if my SCF results fall within the correct range but my GGA results are too low?
25. What should I do if my GGA results fall within the correct range but my SCF results are too high?
26. What should I do if my GGA results fall within the correct range but my SCF results are too low?

1. What is the shelf life of PolySeed NX?

PolySeed NX has a shelf life of 2 years. If your PolySeed NX is close to or has passed the expiration date, you should order a new bottle.

2. What material is my PolySeed NX capsule made of?

The PolySeed NX capsule is made of food grade gelatin.

3. Under what conditions should PolySeed NX be stored?

  1. Temperature range: PolySeed NX should be stored between 65-80°F (18-25°C). If PolySeed NX has been stored outside of this range, microbial activity may be diminished.
  2. Humidity: PolySeed NX should be stored in a dry area. If PolySeed NX is stored near a moisture source, microbial activity may be diminished. If the product inside the PolySeed NX capsule is difficult to pour into the dilution water, your PolySeed NX may have absorbed moisture in storage.
  3. Location: PolySeed NX should be stored away from any source of heat and light. This includes ovens, autoclaves, furnaces and direct sunlight.

NOTE: When storing PolySeed NX , make sure the bottle is closed tightly. If the bottle has not been kept closed, environmental conditions may adversely affect microbial activity.

4. How many individual tests can one capsule of PolySeed NX perform?

One capsule of PolySeed NX per 500mls of dilution water can be used for 100-125 tests depending on the amount of seed used per test.

5. Are there any nitrifying organisms in PolySeed NX?

No, PolySeed NX is made from pure sporulated cultures containing no nitrifying organisms. To survive, nitrifiers must have moisture. The bran that acts as a carrier for the microbes in PolySeed NX is not conducive to nitrifier growth.

6. Is the chemical inhibitor (Allylthiourea i.e. ATU) used in PolySeed NX approved for use by Standard Methods?

Yes. The 21st Edition of Standard Methods approves the use of ATU for the CBOD test.

7. How do I rehydrate PolySeed NX?

  • Open the PolySeed NX capsule and pour the contents into 500mls of dilution water. (We recommend 500 mls however, this amount may be adjusted to achieve a SCF between 0.6-1.0mg/L)
  • Aerate the PolySeed NX solution for 1 hour using an aquarium pump and diffusers (the vortex method is not recommended) while mixing on a magnetic stirrer.
  • After aerating and stirring for 1 hour let the PolySeed NX solution settle for 15 minutes (in the beaker or in a separatory funnel)
  • Decant the PolySeed NX solution to eliminate the bran. You can slowly pour your solution into a clean beaker or you can use a separatory funnel.
  • Place the PolySeed NX back on the magnetic stirrer and gently stir throughout the remainder of the test. This will keep the solution from stratifying.

8. What type of water should I add the contents of the PolySeed NX capsule to?

The PolySeed NX capsule must be added to BOD/nutrient water only. The BOD/nutrient water is used for ionic balance. The chemical balance inside each microbial cell in the PolySeed NX must be equal to the chemical balance in the water surrounding the cell. If the microbes in PolySeed NX were rehydrated in plain deionized water, the differential pressure between the water phase outside and inside the cells will cause the cells to lyse (explode/tear) within a few minutes.

9. Can I use deionized water to prepare my PolySeed NX solution?

No. The PolySeed NX solution must be prepared with BOD/nutrient water only. The BOD/nutrient water is used for ionic balance. The chemical balance inside each microbial cell in the PolySeed NX must be equal to the chemical balance in the water surrounding the cell. If the microbes in PolySeed NX were rehydrated in deionized water, the differential pressure between the water phase outside and inside the cells will cause the cells to lyse (explode/tear) within a few minutes.

10. When preparing the PolySeed NX solution, can I just drop my capsule into the dilution water?

No, the PolySeed NX capsules are not readily soluble. To use PolySeed NX, you must open the capsule and pour the contents into the dilution water. For optimum activity, ensure that all of the capsule contents are added to the dilution water.

11. Should I start my test over if a piece of the PolySeed NX capsule falls into the dilution water?

Yes. Although the capsule is made of food grade gelatin, we recommend you start over. The BOD test has many variables and you don't want to take any chances.

12. If bran is introduced into the BOD bottle will it adversely affect the 5-day dissolved oxygen uptake rate?

Yes. The bran is simply a carrier for the microbes. Once the PolySeed NX is hydrated, the microbes soak off the bran. The bran is not a primary food source. Bran should not be present in your test; therefore it is very important not to draw any bran into your pipette. This is why we highly recommend you decant your PolySeed NX solution after the solution has been hydrated.

13. How long is my prepared PolySeed NX solution good for?

The PolySeed NX solution will remain active for up to 6 hours. If you test runs over 6 hours, it is necessary to prepare fresh solution.

14. What dilutions should I use when performing the test?

Dilutions Summary

  • Use 2 dilution water blanks
  • Use 3 Seeded controls - preferably, 15, 20, 25 ml PolySeed NX solution & fill to 300 ml with dilution water. However you can adjust these dilutions based upon your experience. For instance, we use 20, 24, 28 ml of PolySeed NX for our seeded controls.
  • Use 2 Glucose/Glutamic acid controls - 6.0 ml GGA solution, 4 ml PolySeed NX solution & fill to 300 ml with dilution water.
  • Add 4 ml PolySeed NX solution to each sample bottle.

Note: We monitor PolySeed NX at these dilutions, as they are the ones used most commonly in labs all over the world in order to meet Standard Methods criteria. The calculations from these controls can help us determine conditions in your lab to help you meet criteria.



15. What type of BOD bottles should I use?

To ensure a water tight seal, InterLab Supply recommends using Wheaton’s 300-mL BOD bottles.  Wheaton’s BOD bottles have a flared mouth and use tapered ground-glass stoppers which are the bottle features recommended in The Standard Methods for Examination of Water and Wastewater.

16. What should the DO depletion be for the largest volume of PolySeed NX solution (25 mls)?

It is important that the largest volume of PolySeed NX solution deplete the DO by at least 50%. This indicates good microbial activity in your PolySeed NX solution.

17. Is the 5-day Dissolved Oxygen Uptake associated with the microbes or the bran?

The dissolved oxygen uptake rate (DOUR) is associated with the microbes in PolySeed NX. The bran is simply a carrier for the microbes and not a food source, although it can be with time (normally over 6 hours). Once PolySeed NX is hydrated, the microbes soak off of the bran. No bran should be used in your test so it is very important to not draw any bran into the pipette.

18. Why is it common for the GGA standard to fail low when running a CBOD?

The chemical inhibitor used in the CBOD test (TCMP or ATU) can have a toxic effect on bacteria, commonly causing lower GGA results. To solve this problem simply add more PolySeed NX to compensate for any bacterial loss that may occur.

Note: Standard Methods states: "When nitrification inhibitors are used, GGA test results falling outside the 198 +/- 30.5 control limit quite often indicate use of incorrect amounts of seed. Adjust amount of seed added to the GGA test to achieve results falling within this range."

19. What should I do if I get High SCF and High GGA results?

Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

Increase PolySeed NX rehydration dilution water by 50-250 mls. This process is approximately linear so if you need to reduce the SCF 20% you should increase the dilution water by 20%.

After this adjustment and your SCF falls into range but you are still having problems with high GGA, decrease the amount of seed in your GGA's and/or samples by 1-2 mls which will lower the GGA.

20. What should I do if I get High SCF and low GGA results?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

Increase PolySeed NX rehydration dilution water by 50-250 mls. This process is approximately linear so if you need to reduce the SCF 20% you should increase the dilution water by 20%.

After this adjustment and your SCF falls into range but you are still having problems with low GGA, increase the amount of seed in your GGA's and/or samples by 1-2 mls which will increase the GGA.

21. What should I do if I get low SCF and High GGA results?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

Decrease PolySeed NX rehydration dilution water by 50-250 mls. This process is approximately linear so if you need to increase the SCF 20% you should decrease the dilution water by 20%.

After this adjustment and your SCF falls into range but you are still having problems with high GGA, decrease the amount of seed in your GGA's and/or samples by 1-2 mls which will lower the GGA.

 

22. What should I do if I get low SCF and low GGA results?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

Decrease PolySeed NX rehydration dilution water by 50-250 mls. This process is approximately linear so if you need to increase the SCF 20% you should decrease the dilution water by 20%.

After this adjustment and your SCF falls into range but you are still having problems with low GGA, increase the amount of seed in your GGA's and/or samples by 1-2 mls which will increase the GGA.

23. What should I do if my SCF results fall within the correct range but my GGA results are too high?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

If your SCF falls into range but you are having problems with high GGA, decrease the amount of seed in your GGA's and/or samples by 1-2mls which will lower the GGA.

24. What should I do if my SCF results fall within the correct range but my GGA results are too low?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

If your SCF falls into range but you are having problems with low GGA, increase the amount of seed in your GGA's and/or samples by 1-2mls which will increase the GGA.

25. What should I do if my GGA results fall within the correct range but my SCF results are too high?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

If your GGA falls into range but you are having problems with high SCF, increase the PolySeed NX rehydration dilution water by 50-250 mls. This process is approximately linear so if you need to decrease the SCF by 20% you should increase the dilution water by 20%.

26. What should I do if my GGA results fall within the correct range but my SCF results are too low?

• Is the GGA fresh and of high quality? Always insure that the GGA solution has not expired and has not been contaminated. Remember, exposure to air can biologically contaminate the GGA solution.

Has your labware been properly cleaned? Always properly clean and store your bottles, pipettes, tubing, air stones, etc. Sterilization of air stones and tubing is not recommended.

Has your technique changed? Make sure that your technique is proper and consistent, paying special attention to your pipetting technique.

Have you checked the water quality? The DI/Distilled water pH should be between 6.5 and 7.5 with a conductivity of less than 1.0 micromhos. The BOD water pH should be 7.2+-0.2 with a conductivity of 125 - 160 micromhos.

Finally, have you reviewed and are properly following the current PolySeed NX application procedures? A copy of these procedures is provided with each bottle of capsules or liquid and should be reviewed regularly for changes. These procedures can also be downloaded from our website.

Next, after the above has been addressed and problems still exist, do the following:

If your GGA falls into range but you are having problems with low SCF, decrease the PolySeed NX rehydration dilution water by 50-250 mls. This process is approximately linear so if you need to increase the SCF by 20% you should decrease the dilution water by 20%.

 

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