Cycling cold water tank...

[Cecil B.]

I'm going to hatch trout eggs and grow out fry and fingerlings in a recirculating system which is basically a larger version of an aquarium. I have had lots of experience with warm and cool water fish doing this smallmouth bass, bluegill, yellow perch, and tilapia and of course cycling the tanks.

However the water temps will have to be quite low for the trout eggs (low to mid 50's F. or 10 to 12 C.) vs. the warmer water in this tanks.

I can use media that already cycled from my other tanks but am hesitant because

1. There may be pathogens present in the media the trout have not be exposed to

2. My thinking is the bacteria that was cycled in 70 to 80 degree water may not be the same bacteria I want or need for the cold water.

What would you do? Use the media anyway or start from scratch feeding the media ammonia (fish less cycling) until it appears the media is cycled for the cold water.

Another possibility is since this will be partial flow through (I have access to high quality well water that comes out of the ground at 51.6 F. (10.9 C.) I can ameliorate any toxic effects of ammonia or nitrites at least initially by augmenting with the well water? I will have to anyway, to keep temps down, although water temps in the basement without heating usually sit at 62 F. (14.4 C) during the winter.

Thoughts?

 

[Drstrangelove]

Nitrobacter and nitrosomonas do work at 50F, but reproduce and work much slower. They stop working at 39F and they die at 32F. I haven't switched from warm water to cold water tanks, but I don't see why you can't use mature media from a warm water tank.

As for pathogens, I'm not sure they would be different. Ich for example exists in ranges well below 60F, although it's reproductive cycle is extraordinarily long at low temps. (One cycle takes 8 weeks at 43F.)

Good luck with the eggs.

 

[Cecil B.]

I opted to sterilize. Just don'ts want to take a chance. Am starting over with the sterilized media but ordered some bacteria from Pentair/AES, since it's supposed to speed things up and hasn't been exposed to fish. I will probably have to start out with flow through and then add the media once it's cycled in a separate moving bed tank.

 

[Cecil B.]

Sterilized media completely cycled in 3 weeks by using the bacteria from Pentair/AES. Been feeding it on capful of ammonia per day and it's gone by the next day. May be gone much faster but I don't test until the next day. Water is about 65 degrees right now. Trout eggs should be coming either this week or next at the latest.

 

[duanes]

I worked for a water company that used chloramine as a disinfectant, so ammonia was added to the water to create to create chloramine. The distribution system was tested and found to have biofilm populations of ammonia using bacteria. The water temp averaged 50'F but dropped much over in winter, and seldom reached to 70'F in summer. The source was a very large stable body of water
So, it would seem to me, you'd want to grow your population at the temp the fish will be living, and would be much more efficient than growing your beneficial population at 70 - 80'F where a drastic temp change could cripple and maybe kill a large portion. Bacteria are sometimes very sensitive to temp fluctuation.

 

[Cecil B.]

Interesting about the chloromines and the bacteria that were feeding off the ammonia. Fortunately the two high schools I have set up RAS' , that use municipal water, don't have the water treated with chloromines. I say that because it would make neutralizing the chloromines for make up water more of an issue.

As far as cycling at lower temps, that the trout would be in, that was my thinking too duanes, but I was in a time crunch and needed to cycle ASAP. So, since a reliable source said it's the same bacteria, I decided to cycle at higher temps to get it cycled quicker, which was the case. Then I just removed the heater and let temps drop to the room temp of 65. Now the media is in 53 F. water with the use of a chiller.


So far so good, at least with the eggs. No ammonia or nitrite readings. And the eggs are hatching in a much smaller volume of water due to a leakage problem with the 150 gallon circular tank. I think it may be a cracked bulkhead fitting where the center drain is.

Getting a new tank soon to get everything back up an running. Right now the eggs are hatching in a makeshift blue drum fed by another blue drum bifilter with about 3 to 4 cubic feed of biofilter media, and a third barrel which the chiller and pump is associated with. I also have an airstone in the bottom of the barrel with egg basket. Was using DIY egg hatching jars in the larger tank but there is no room in the barrel. so instead I cut the bottom and sides out of a small laundry basket and installed nylon screen. I like it better than the jars as it's easier to see and pick out the dead eggs.