Continuous Recirculation During Cold Water Extraction

One of the things that we talk about most often is continuous recirculation during agitation in your ice water extraction vessel. All Hashtek ice water systems are setup to be compatible with continuous recirculation including the A-series and T-series. Pictured below is the A-series setup for continuous recirculation.

The primary principle behind continuous recirculation is protecting your heads:

By continually pulling water out of the agitation tank and replacing it with filtered water (during agitation) you are removing trichome heads as soon as they are decapitated from the stalk. This removes sensitive trichome heads from the agitation tank where they are liable to being damaged, and keeps them in the collection vessel where they are safe. This is as opposed to batch style agitation where you agitate for 15-20 minutes and then do a pull.

Aleks – Hashtek Founder

There are also secondary advantages to continuously recirculating during agitation.

Increased Capacity – Continuous recirculation allows you to put the majority of your ice in the collection vessel instead of the agitation vessel. By continually moving water from the agitation vessel to collection vessel you will be chilling your process water to 32F (0C) or colder! Think of it as a river continually running over a stream of frozen ice. Less ice in the agitation tanks means more room for flower.

Pulls Based On Hash Collected – In batch style agitation the hashmaker picks a somewhat arbitrary time for each batch (usually 15-20 minutes) and that is when they collect (or pull) hash from the filter bags. With continuous recirculation you do your pulls when the bags start to clog enough that recirculation becomes difficult. With strains that give up their heads easily you may find that you don’t need to agitate for anywhere near as long. Continuous recirculation gives you more feedback on what is going on in the tank and how quickly the heads are coming off.

Increased Efficiency – In our continuous recirculation setups the agitator never stops working. We set the spin time to 45-60 minutes which represents the full wash time. When the bags start to clog we stop reciruclation but keep agitation going. While doing the pull the agitator is still working – meaning no downtime during the time you are collecting hash.

Continuous Recirculation Considerations

There are some considerations to be made when doing continuous recirculation:

High yielding strainsStrains that yield 4-5% or more on fresh frozen may pose challenges with continuous recirculation as they will be clogging the bags much more quickly. While this is a good problem to have you may find that it helps to do batch style for the first part of the wash in order to reduce the overall number of collections necessary. Typically you do not want to do more than 4 collections on a given run as it can become time consuming and reduce efficiency.

Top Down Agitation Required – bottom impeller driven machines are not compatible with continuous recirculation. This is because the bottom positioned impeller creates shearing forces that damage trichomes. This effect is compounded if you are continually forcing trichome heads down with continuous recirculation. This is a big part of why all Hashtek systems are designed for gentle top down agitation!

Hashtek at The Smoking Jacket

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