Tank VS Shower System– Which is Best?
One of the most common questions I get asked by the lobster industry is whether a ‘shower system’ is the best way to store lobster. It seems that the general consensus in the industry is that the shower system is better for the lobster. Let me unwrap this myth.
First, what do I mean by tank or by shower system? The tank system of holding is self-explanatory. Lobster are submerged in a tank. Water is pumped through the tank. The ‘shower system’ consists of putting a stack of totes or trays under a stream of water that enters the top tote/tray and trickles down through the stack, exiting from the bottom tote/tray.
The tote or tray is designed to stay full of water such that the lobster are continually submerged.
There are two main points to understand in the shower system vs tank debate:
1. A shower system is more expensive to build and to operate
2. Both options can work with zero mortality if the system and is designed and managed correctly
The Extra Capital Costs of a Shower System
To build a shower system, you are going to need a reservoir. A reservoir looks like… a tank. If you are going to build a tank, why not put lobster in it and have it pay for itself? The shower system ends up costing more to build because:
1. You have to build a tank and pump water in and out of it.
2. You have to buy containers specific to the system (trays or totes that keep the lobster submerged in water).
3. Piping supply and install is higher as a manifold mounted to the ceiling is required above the storage area, and a collection system is needed in most systems.
4. Pumps are bigger as it costs more to pump water 8-12 ft vertically to the top of the shower system as compared with a tank where lift may be 1 to 2 ft vertically.
5. Chillers have to be larger as the ‘shower’ action exposes exponentially more water surface area to the air resulting in more rapid heat gain in the water.
6. You may not need a blower, but that is typically the cheapest piece of equipment you buy for a tank.
The Extra Operating Costs of a Shower System
To operate a shower system, you are going to face the following extra costs as compared with a tank:
1. Cost of handling (labor and quality affected): floating crates that the lobster are typically brought in cannot be put directly into the shower system without creating weaks/deads. Without an extra handling step of transferring the lobster to the proper tote or tray, lobster quality will suffer. But handling also causes quality to suffer…
2. Higher energy costs: see items 5 and 6 above.
3. Lower water quality: the nature of the shower system is such that there is a gradient of water quality from the top of the stack (good water hopefully) to the bottom of the stack (poorest water quality). The metabolic wastes from the lobster on top get washed down to the lobster on bottom. This translates to a gradient of lobster quality from top to bottom of a stack. In a tank, proper hydraulics allows the waste to be flushed to the drain.
Benefit of a Shower System
There is really only one benefit of shower systems that I have seen… the ability to fit more product into the same footprint by building one on top of an existing tank, or where a tank cannot fit. If you have a tank, it may be possible to increase the size of your operation by building up rather than finding space to build a new tank. This allows you to use the same building, the same working area, the same loading area, and the same equipment area (some equipment will have to be added). Often, it is possible to double the holding capacity of a tank by adding the shower system on top of the tank. The tank continues to be used as before.
Tank VS Shower System
When it comes to lobster quality, both can be made to work. It is possible to find users of each system that have success and users of each type of system that have 2% or more chronic mortality and shipping issues. The truth is, if you tell me what type of system you want to use, it can be designed to work well and you can be trained to run it well. But a stand-alone shower system is going to cost you more to build and operate.
My recommendation is almost always to build a tank that functions as a live holding tank. The option to build up with a shower system is always there… either on day 1 or years later.
At Aqua Production Systems, we use cutting edge aquaculture methods to design/build or retrofit any style system so that it works (by “works” we mean zero mortality claims). Call us at 902-746-3855 to discuss how your system “works”.
PS: Two to three percent mortality from holding tanks is embarrassingly unnecessary. By fixing water quality, my customers get two to three dead lobster from their tanks, not 2-3%.
Philip Nickerson, B.Eng.