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One open cell comfort-cooling tower manufactured by Marley located on the building roof four floors above the ground. The cooling tower system was part of a new construction package and had been in operation for one year with no bleed-off or chemical treatment.
The tower basin was extremely dirty. A visual examination indicated the start of sulfate-reducing bacteria (SRB). Follow-up testing was done using the Hach SRB BART test with positive results in 48 hours.
The tower system was flushed and drained. The SRB nodules were scraped and brushed. Nodules under the fill were knocked loose using a metal rod. The tower basin was vacuumed to remove all loose material. The system was refilled and both UKP-10 and UKL-06 were added at maximum dosages and circulated for 6 hours. The chemical treatment program consisting of HS-4230, C-366 and AA-315 was started. The C-366 was fed every Monday and the AA-315 was added every Thursday.
Since the initial physical cleanout and addition of the UKP-10, SRB have not reappeared. Alternating C-366 and AA-315 on a weekly basis has been effective in controlling new growth.
Note: Do not add C-366 and AA-315 in the system at the same time. These two products are not compatible with each other.