Water from Dale Hollow Lake carries some hydrogen sulfide, manganese, a number of single celled parasites, low oxygen, and other compromised water quality factors as the lake is lowered prior to the low energy demand and rainy season. Once the lake ‘turns over’, water temperatures at the hatchery will drop and water quality will begin to increase. The period of lowered water quality directly impacts egg, fry, fingerling and adult fish survival rates.
The hatchery tank room houses 25 concrete raceways coated in pool epoxy paint. This paint is stained black from the manganese load in the water and one of the non-invasive things the crew does to try to increase fry rearing water quality is to scrub these raceways between uses. The only thing we’ve found that works consistently/quickly is elbow grease. Ajax, scouring pads, and hand scrubbing takes off the black deposit layers. This year we’ve added using pads on drills to compliment the effort. There are cons to other potential methods being evaluated:
- Steam: investment cost and uncertain results
- Repainting: down time and limited applicability
- CLR: down time for a soak to take effect and uncertain removal rate
- Hyperchlorination: chemical usage and discharge risks