Manchester Conditioning Update 6

Power outage edition

But first, let me walk you through what I did before the power went out.

On Monday, Laura vacuumed my oysters and increased the temperature. She also fed them 1.5 L of Reed’s paste. On Wednesday, she saw that the left heater was on, but wasn’t heating. She unplugged it and plugged it back in. She also increased the setpoint to bring the water back to the temperature it was at, around 21 ºC. Temperature spiked around 22 ºC, then leveled back down to 21 ºC. Because we were running out of Reed’s paste, Laura fed 225 L of Tetraselmis and 1 L of Reed’s paste. She also moved Durafet 1 into Tank A, supplementing the Durafet already in Tank B.

Today, I drained and rinsed the oysters and oyster tanks. I found 3 mortalities: 1 from Tank 2A and 2 from Tank 4A. It’s a bit weird that most of my mortalities have been from Tank A…

Table 1. Revised oyster counts in each tank.

Tag Label A B Total
1 7 9 16
2 8 8 16
3 6 6 12
4 7 7 14
5 9 8 17
6 7 8 15
Heat Shock 5 6 11
Full Amb 7 8 15
Spare 2 3 5
Total 58 63 126

When cleaning the heating tank, I noticed that the Reed’s paste was much clumpier and globbier that it normally is. I think mixing it with Tetraselmis is changing the clumping pattern. When I fed the oysters today, I grabbed about 600 mL of Reed’s paste from the little we had left and mixed it thoroughly with about five gallons of water. I did this to dilute the Reed’s a bit more before mixing it with Tetraselmis. I then added in 100 L of Tetraselmis and topped off the algae header tank with freshwater.

The setpoints I left the heaters at got the water temperature to consistently fluctuate between 20ºC and 21 ºC.



Figures 1-2. Heater setpoints upon arrival.

I increased the heater setpoints, as well as increased airflow to all tanks.



Figures 3-4. Changed heater setpoints.

When I looked at the Durafet monitor, I noticed that the two probes were reading different pH values. Both tanks receieve the same water, so unless one tank is really respiring a lot more than another, this doesn’t make sense. I placed both probes in the same tank and saw that they were registering different pHs in the same tank.


Figure 5. Durafet probe readings for water in Tank A.

I measured the flow rate at about 100 mL in 15 seconds, or 400 mL/min for each tank, which is pretty low. Before I had any time to think about it, the power went out! Apparently, a pipe burst and flooded the main power conduit. This meant that our power, even backup power, to the hatchery was gone. Our heated line was out and there was no water flowing to our tanks. We had to quickly ensure we could get water to our animals.

The first thing we did was switch our water over to the ambient lines. We temporarily unplugged our water heaters to plug in the mixing valve and allow the cold water to flow through. We also removed the one micron filter because it would get clogged too fast. Using an extension cord, we plugged in all of the heaters and probes so we can have heated water for the C. gigas and remote monitoring. We plugged in our dosing pumps and Laura’s water heaters into a power box as well.


Figure 6. Temporary set-up for dosing pump power.

Because the ambient line is colder than the 14 ºC heated line, I ramped up my heater setpoints, hoping to maintain the water temperature anywhere between 20 ºC and 22 ºC.



Figures 7-8. Heating setpoints after power outage.

Before leaving, I checked the Durafet monitor to see how the pH and temperature were holding. The temperature was reading at 22 ºC, so I think we’re going to be okay!


Written on July 13, 2017