5000 GALLON CONSERVATORY PART 2: Purifying and Clarifying

Once drawn from the surface, the water flows down to a 500 gallon sump filter fabricated from acrylic. This filter acts as both mechanical and biological filtration. The filter is designed in such a way where the water passes through weirs, which aid in lengthening the path of water through the biological filtration. The water is clarified as it resides in this sump. At the very end of the filter there is another sump pump that returns the water form the last section of the filter back to the first. This parallel loop is for water to be heated as well as UV sterilized. This is much more efficient way of heating and sterilizing the water that passes through this filter. Putting these extra components on a parallel loop instead of in series helps to decrease the amount of work the main return pump has to perform, as well as to maintain the maximum amount of water pressure returning to the pond. The idea is to have clean water returning back to the pond, water that is clarified, detoxified, UV sterilized, heated, and oxygenated. 

We collaborated with California Acrylic Design in Mid City Los Angeles. These guys are great. They are highly skilled and are flexible when it comes to the constant design changes as what occurs with any custom one off projects. The sump filter was constructed entirely out of acrylic and bonded with specific solvents. After weeks of drafting up different designs and running through theoretic operations of each, I’ve made my decision. Trying to steer away from any overcomplicated designs, I wanted to keep it simple without sacrificing efficiency and keeping ease of future maintenance in mind.

Once the 500 gallon filter was set in its permanent place, then began the plumbing. Though only water was to be running through the system, schedule 80 PVC was installed throughout. With a tight space to work with, routing the 2 inch lines were a little tricky. The filter feed line from the pond governed the placement of the filter as well as the return pump. shutoff valves and T's needed to be strategically placed for maintenance purposes and to leave room for future upgrades or changes. The scope of this project did not include running new PVC piping from the pond to the equipment room, the method of filtration was the only thing reengineered. 

A complication in calculating the dimensions of this filter was that theoretically a sump filter feed needs to reside at a lower level than the pond to be fed by gravity, and the exact level of the pond with respect to the equipment room was unknown. After some estimations and simple tests with water, the room was determined to be lower than the pond. This allowed me to calculate exactly how high I can route the filter feed line to the filter. Trying to cover all the bases, an emergency overflow line was plumbed to a drain. It wouldn't be good if we had a power outage and a flooded equipment room. This wasn't an issue in the previous design since it was a closed system. 

Transitioning from the method of an under gravel filtration through a sand filter to one that drew water from the surface of the pond gravity feeding a sump filter was the goal. There were several benefits to encourage this change in design. The first was to increase the amount of biological filtration that the previous system lacked, especially if the pond is intended to have a large bioload. In other words, the filtration needs to handle the chemistry of the water appropriately for a system that will potentially incur large amounts of bacteria, organic material, waste, and other matter that is dissolved in the water column.

An advantage I had in mind when installing this type of filtration was the option of adding other components to the system out of sight from the pond itself. In a parallel loop, a second pump pushes water through an inline heater and UV sterilizer back to the first section. This filter heats and sterilizes the water more efficiently as opposed to the previous design with these components in series going to the pond and back around. To try to put it more simply, it's easier to treat 500 gallons of water than 5000 gallons. 

The first section is used mainly for mechanical filtration consisting of filter floss to separate the larger detritus material that the filter baskets in the pond let by. The 3 middle sections consist of thousands of bioballs. Bioballs? Yes bioballs. They are ribbed plastic spheres with an increased surface area for beneficial bacteria to grow on. This bed of bioballs helps culture nitrifying bacteria that detoxifies the water by converting ammonia to nitrite and then to nitrates. This is a natural process that helps keep the system's water clear and safe for its inhabitants.

The beneficial bacteria will culture under the right conditions. With the right temperatures and oxygen rich water, the bacteria can thrive. With the warm temperatures and the oxygenation from the filter feed, this system creates the perfect environment within its own design. With time, the preventative maintenance frequency of the filtration system would be determined.

The filter floss may get clogged and the rate of water able to pass through will decrease over time. The bioballs themselves may accumulate particulates and begin to clog as well. Routine flushes of the filter may be needed. In case of a failure for any of the components, there would be a shutoff or bypass that could be made so that the pond would stay unaffected. What flows down to this filter is altered to have the desired properties.  The filter was designed with maintenance in mind.