Backyard Aquaponics
A place to discuss aquaponics

I went over to the tank with my daughter this morning, trying to beat the heat, and we installed the 'tank curtain', although it is more of a skirt.




It will no doubt make some difference to the water temperature of the tank but, with the extended hot spell that is forecast for the next several days, it may not make enough of a difference to enable my trout season to be prolonged as I planned. I think a greater air gap between skirt and concrete wall would work better but it was easy to attach it this way, ie pretty much flush.




The entire concrete tank area will be much more shaded next year when my bamboo screen will be at least twice its current height. It has just this month started to accelerate its growth.

Hi PLJ love the bamboo screen. I wish I had the water to grow bamboo but unfortunately with only tank water its not an option.

My Concrete Rain water tank is at 17C ATM. Tank is 100 000l and about half full. The lined 100 000l metal tank is full and about 18C. They are part shaded by trees so it does have a positive effect. Once they warm up they take ages to cool down.

With the new skirt in place it very much looks like a purpose made aquaculture tank. Very sexy.

I'm pleased you like bamboo, Marc. In your soil you may well be able to keep a drought tolerant species going, perhaps with a bit of help here and there until it is established. Probably the best in your situation is Buddhas Belly Bamboo (Bambusa ventricosa), which is very tough.

Your shade trees must make all the difference, Marc, because my tank water is much warmer than 17-18 ºC. I have just come back from topping up the tank and am shocked at the warmth of the water. The trout fed this morning but showed nil interest tonight.

As you say, tanks don't cool down in a hurry so I reckon the new skirt may prove to be too little too late, as far as keeping the tank cool is concerned.

Charlie, I like a sexy skirt, too, but this old girl had her skirt down for too long, I fear - she is now just too hot to handle.

Despite the frighteningly warm water in my tank I have seen no signs of stressed fish at the surface. They often take a few pellets when I throw them in, even in the middle of the day. Some quite small ones occasionally leap out of the water as they feed, as they all did previously, but generally it is more of a sedate slurp of the pellet that hey employ when feeding. I get to see the size of them this way and am sure that there are a couple of monsters - well, bigger than I have yet caught - in there.

I caught five Rainbows on Saturday night and four last night, including these two pictured. They weighed a touch either side of 500g. Something interesting that I noticed is that they leave a lot more slime in the net now the water is warm.

It amazes me that I can catch any at all with my blind scoops in the same patch of water from my ladder. There can be no more than one trout per 2,000L of water yet I scoop randomly in the dark and somehow they find their way into my net, sometimes two at a time. I'm not complaining.

Hello from Colorado, USA. Very interesting thread, I've read it in it s entirety over the last coupl'a days. Like a fair few of others posting here I am a bit green with envy , not only for your tank but, also your climate. Here it has been roughly 1 degree C at daytime and -26 at night. Seems like a dream to be able to do this outside year round (provided you change your fish species I gather). Anyway love the thread immensely enjoyed the read!
Jared

Hello Jared, thanks for the compliment of reading through the entire Big Concrete Tank thread. I am very glad that you enjoyed it.

I can't even comprehend the kind of temperatures that you are talking about in Colorado. I shouldn't complain about our weather here, just because of a succession of stinking hot days around 40 ºC, because it is pretty darn good, generally. Anyway, it is not long before your winter solstice and then you will be on the downhill run towards summer again, yourself.

All the best with your AP dreams.

I fear I am losing the battle to keep Rainbow Trout in my tank through to the new year. Several were cruising the surface, dorsal fins proud of the water, by late yesterday afternoon. Ironically it was the 16 Dec last year when the hot weather forced me to drain the tank in order to catch the last 20 or so of my first batch of trout.

The kids and I scooped out the 10 cruisers just in case they decided to become floaters by tomorrow. According to my records there are still 35 trout unaccounted for. With slightly cooler weather for a few days and the replacement of a few thousand litres of tank water with cooler bore water, I may yet be able to get some trout through into January and perhaps beyond that hurdle to conditions that see the trout feeding once more.

What is the temperature difference from top to bottom of the tank?

Very little, Bill, but there is likely to be some difference.

In addition to the inputs from the GBs and drum bioflter I circulate the water from the bottom to the top with a pump in order to create extra splash and some swirl action. Just lately I have only run this pump during the relative cool of the evening because I reckon any water that spurts out above the surface of the FT in the present scorching weather is going to pick up heat before splashing back in. Similarly, water running through the GBs and into the sump is certainly returning to the FT warmer than when it left - I can sense it with my hand. So I let the water sit during the day, stirred only slightly by returning filtered water, and I reckon the trout find somewhere down deep that is at least marginally comfortable for them.

How tall does bamboo grow? From your pictures it looks as if the bamboo is 20 to 30 feet away from your tank. It is going to have to be extremely tall to provide any real shade to the tank?

PLJ - Spray water on the curtain (if that's an affordable option) - the evaporation will help keep the tank cooler. I'm not certain how much cooler but might be worth a try. I'm assuming this won't hurt the curtain so you'll need to check on that.