Cage Wash

The Life Extending Cage Washer Diet Craze

The eastern USA aquifer is comprised of relatively hard water with high mineral content.¹ Calcium and magnesium can be separated from the aqueous solution when heated in a cage washer at 180 degrees F. The liberated minerals may then attach to the cage washer walls, impellors, nozzles, and heat exchangers. If softening the water is not feasible, descaling is an option to remove the deposited liberated minerals in the washer. This article will examine descaling solutions (including those using green compounds) and the benefits of pursuing good cage washer health.

Sources of Scale
There are two main sources for “scale” in the laboratory animal facility use of this term.

Lagomorphs (rabbits) and Rodentia (such as guinea pigs) are known to excrete copious amounts of urine containing mineral deposits, such as calcium, that adhere tightly to the surfaces of the pans and their housing units. The local water may contain dissolved and distributed elements which are useful for life and dietary fulfillment. Groundwater frequently has high amounts of calcium carbonate and magnesium carbonate. Soluble at room temperature, once the water is heated to temperatures beyond 150 degrees F, these mineral bicarbonates begin to precipitate out of solution and are deposited on available hard surfaces. Additionally, they tend to bind with cage wash chemicals, developing “scum” which can block drainage pipes and create biofilm.

The eastern USA aquifer is particularly susceptible to these minerals because of the amount of limestone through which the water flows underground prior to being extracted for consumption.² Simple water test strips can reveal the hardness of the local water source.An easy ‘at home’ way to check domestic water hardness is to lather some hand soap onto a surface and look for frothing. The harder the water, the less foam and froth, and the more agitation will be needed to lather the product.

Effects of “Hard” Water on Cage Washers
Cage washers, by definition, are designed to wash and rinse animal housing units at temperatures above the minimum needed to precipitate the hard water calcium and magnesium carbonates out of solution. Essentially, the washers produce hard water deposits.

Depending on the severity of the water hardness, this can take place over a long period of time or can build up in an extremely short period of time—as little as one or two wash cycles. While the wash chamber may be exposed to some acid treatments during a normal cycle (such as residual pre-treatment acids from hand preparation of the caging unit or to an acid wash), the final rinses generally are house hot water with no added chemical agents.

Tunnel washers may be more intensely impacted because the rinse and dry chambers usually have no chemicals added to the house water.