Seasonal maintenance for gravel media in growbeds

[Garrett Blair]

I'm still in the planning phase of my AP system. I plan to have an attached greenhouse with good southern exposure, I live in a area where trout should be ideal (lakes reigion of NH). I havent built the greenhouse yet, so I'll be fortunate enough bury and insulate my FT or sump tank (still planning). I'm on the hunt for a local intert 3/4" round inert gravel......

My question is this, if I choose to keep my trout in the tank over winter, but choose not to heat my greenhouse to the point where I'll be able to grow veggies, will I need to do anything with the growbeds to prepare for spring planting?  What are the fishes needs during the winter months? I want to include worms in my grow beds, if I can keep the beds above freezing, will the worms survive (and in hand provide the filtering the fish need to survive? Or would I be better off just harvesting the trout, and re-cycling the whole system in the spring?

 

Sorry for the mish-mash of questions, Thanks for any feedback.

Garrett

[Jon Parr]

If the growbeds don't freeze and kill the bacteria, and if they frequently get over 50 F (so they wake up and get busy), then nitrification will still happen and you will be fine. Keep a close eye in chemistry, especially when it's the coldest. Or so I'm told. I don't keep trout, but I do keep sturgeon, and they are also cool water creatures.

[Garrett Blair]

Good to know it can be done. I just have to decide on a plan. Do you harvest your sturgeon?

 
Jon Parr said:

If the growbeds don't freeze and kill the bacteria, and if they frequently get over 50 F (so they wake up and get busy), then nitrification will still happen and you will be fine. Keep a close eye in chemistry, especially when it's the coldest. Or so I'm told. I don't keep trout, but I do keep sturgeon, and they are also cool water creatures.

[Vlad Jovanovic]

My water temps have been consistently in the mid 40's for a good while now and I'm amazed at just how much nitrification is still taking place. The books and studies painted a much bleaker picture, but all is well so far... Definitely like Jon says keep an eye on water chemistry and if you need to adjust your feeding rates, or harvest 'a couple' trout, it's not a tragedy.

Depending on your GH design, you may be surprised on the vegetable end of things too (just by keeping things above freezing)...That is, if you keep it real and stick to plants that are appropriate for the winter season... Growth rates can be far from optimal but still quite OK considering...

[Jon Parr]

Growth can get pretty slow, for sure, when it cools. But Vlad is right, they do keep growing an using nutrients.

I will harvest the sturgeon, yes, and they are awesome eating. They get 12-15 lbs in 3 years, which beats everything else for growth rates, but the fingerlings are pricey. Here in Cali, they are only legal to buy, sell, and transport up to 8" long (to allow the pet trade access to an otherwise restricted fish). I have 25 now, that are about 1/2 lb each, and growing fast.

[Garrett Blair]

Thanks for the feedback, I'm still on the fence between tilapia and trout, my biggest concern is keeping the trout tank  cool enough, I just worry that the temp of the grow  beds in the greenhouse during summer months will warm the fish tank water too much for trout, but then if I go with tilapia, I'll run into the problem of heating the water.....good greenhouse design is crucial.  I'm wondering if a well insulated fish tank (at least 200 gal.) would overheat for trout, and what my options are for cooling during those hot summer days. My first thought is since I have a chest freezer running full time in the basement, take advantage and have a couple blocks of ice to drop in on the really hot days..? I dont know how much ice it takes to drop a 200 gallon tank from say 70 degrees to 55 degrees, or if thats even practical....any thoughts, or am I just over thinking this....
 
Vlad Jovanovic said:

My water temps have been consistently in the mid 40's for a good while now and I'm amazed at just how much nitrification is still taking place. The books and studies painted a much bleaker picture, but all is well so far... Definitely like Jon says keep an eye on water chemistry and if you need to adjust your feeding rates, or harvest 'a couple' trout, it's not a tragedy.

Depending on your GH design, you may be surprised on the vegetable end of things too (just by keeping things above freezing)...That is, if you keep it real and stick to plants that are appropriate for the winter season... Growth rates can be far from optimal but still quite OK considering...

[Garrett Blair]

Jon,

How cold do your winters get? Are you able to keep your fish tank outside year around?  I'm tempted to try to make the trout work, I like the idea of harvesting on demand over a longer period of time vs. a grow/harvest in one season if I can keep the system running year round, thats my preference. I'll keep researching, thanks for the reply.

 

Jon Parr said:

Growth can get pretty slow, for sure, when it cools. But Vlad is right, they do keep growing an using nutrients.

I will harvest the sturgeon, yes, and they are awesome eating. They get 12-15 lbs in 3 years, which beats everything else for growth rates, but the fingerlings are pricey. Here in Cali, they are only legal to buy, sell, and transport up to 8" long (to allow the pet trade access to an otherwise restricted fish). I have 25 now, that are about 1/2 lb each, and growing fast.

[Rob Nash]

you can add some Archea, it will nitrify down to freezing. they say its something like 3000 times more effective at converting ammonia. it can handle extreme heat conditions as well. ...it really helps clear up cloudy water, especially if you ever get soap residue or oil  in the tank water.

http://www.biozome.com/pages/what.html

http://en.wikipedia.org/wiki/Archaea

 

 

[Jon Parr]

Awesome, Rob. Are Archae anaerobic? It probably states that in the wiki link, I didn't have time (attention span) to finish reading. Long day today.

Garret, I'm in a pretty mild climate. It doesn't snow, and seldom frosts. My outdoor, uninsulated, above-ground tanks got to a low this year of 46 F, and are now already in the hi 50's again. In the heat of our equally mild summers, they stay around 80, and even more stable if I were to sink one in the ground (55-75 in ground, in greenhouse, no heating or cooling). Trout and sturgeon both should stay below 70, which isn't hard to do if you are clever in designing your system (well, here at least). Rob is in Texas, so maybe he can chime in on his annual highs and lows.

One thing I noticed earlier is that you wanted an in-ground, insulated tank. I think the insulation may defeat the purpose of having the tank in the ground. You want the stable temp of the earth to help regulate water temp, so dirt/tank contact is desirable. In the winter, you can stop circulation so the cold beds don't cool the FT. In summer, you can circulate all night, just to cool the FT, or even circulate water through some coils exposed to the night air. Of course, here at my place it always cools at night, even in the summer.

[Garrett Blair]

Looks like everyone should use that stuff.  Do you know if its something that you just introduce to an allready cycled system, or is it something that you would use to acually cycle the system from the start? I like that it will handle the temp swings, have you used it?  
 
Rob Nash said:

you can add some Archea, it will nitrify down to freezing. they say its something like 3000 times more effective at converting ammonia. it can handle extreme heat conditions as well. ...it really helps clear up cloudy water, especially if you ever get soap residue or oil  in the tank water.

http://www.biozome.com/pages/what.html

http://en.wikipedia.org/wiki/Archaea

 

 

[Bob Campbell]

@Rob - Thanks for the info on Archea.  I'm going to place an order tomorrow!  

Rob Nash said:

you can add some Archea, it will nitrify down to freezing. they say its something like 3000 times more effective at converting ammonia. it can handle extreme heat conditions as well. ...it really helps clear up cloudy water, especially if you ever get soap residue or oil  in the tank water.

http://www.biozome.com/pages/what.html

http://en.wikipedia.org/wiki/Archaea

 

 

[Garrett Blair]

Jon,

I see what you're saying about the tank insulation. You're right, the dirt contact would help during both seasons. and I never thought about the night time temps offsetting the hotter daytime temps either.  I think insulating the top of the tank (when needed) will help daytime over-heating in the greenhouse. I havent committed to a plan yet, but I really like the idea of the pump running continuous with an auto-siphon, that would deffinately help regulate the tank temp over night.

Is it safe to assume that if I stop circulation in the grow beds during the winter months I'd need to clean the media and re-cycle the system in the spring, or will just recirculating the grow beds be sufficient? probably depends if they get below freezing (killing the good bacteria)? Thanks again for the feedback,

 

I'm slowly gaining confidence in my over all plan.  My next biggest hurdle is going to figure out how to control the winter humity in an attached greenhouse in New England.  (trying to avoid ice on my dining room windows) I'll jump into a different forum topic for that one.

 
Jon Parr said:

Awesome, Rob. Are Archae anaerobic? It probably states that in the wiki link, I didn't have time (attention span) to finish reading. Long day today.

Garret, I'm in a pretty mild climate. It doesn't snow, and seldom frosts. My outdoor, uninsulated, above-ground tanks got to a low this year of 46 F, and are now already in the hi 50's again. In the heat of our equally mild summers, they stay around 80, and even more stable if I were to sink one in the ground (55-75 in ground, in greenhouse, no heating or cooling). Trout and sturgeon both should stay below 70, which isn't hard to do if you are clever in designing your system (well, here at least). Rob is in Texas, so maybe he can chime in on his annual highs and lows.

One thing I noticed earlier is that you wanted an in-ground, insulated tank. I think the insulation may defeat the purpose of having the tank in the ground. You want the stable temp of the earth to help regulate water temp, so dirt/tank contact is desirable. In the winter, you can stop circulation so the cold beds don't cool the FT. In summer, you can circulate all night, just to cool the FT, or even circulate water through some coils exposed to the night air. Of course, here at my place it always cools at night, even in the summer.

[Jon Parr]

Media beds are fine overnight without circulation, heck they are fine for many days as long as they are moist and within temperature ranges. The FT will need extra aeration if the water quits circulating, since it's not getting the air from the flood and drain. Most folks, including myself, keep pumps on non-stop in greenhouses, because everything stays the most stable that way, especially if night time lows threaten to freeze the growbeds. Insulating the top of the FT is great, just remember that when ALL pumps stop (power failure or mechanical snafu) the covering (especially if it touches the water's surface) may inhibit natural surface gas exchange, and your fish will have only minutes before O2 is depleted. 

If you abandon the growbeds entirely during the winter, you will also have to harvest the fish as well, or reduce stock and quit feeding them, because you will not have the denitrification engine of the growbeds. Yes, they will probably die over the winter, certainly if they dry or freeze, and you will need to re-cycle in the spring. Usually this is painless, as there are often at least some bacteria that is dormant, not dead, and if the FT was kept in good health, then the bacteria are present in the water and will quickly repopulate the media. You shouldn't need to clean the beds every spring, unless they are simply clogged up. 

Now, humidity is a bitch, and personally I just deal with it by exchanging as much air as I can when it warms up, and let it "rain" inside when it's cold outside. If you have the luxury of insulation, then it is much better. There are multi-wall poly-carbonate clear panels for glazing that are great. They even have a non-condensate surface on the inside. And of course they are expensive, easily $2-4 per sq ft for panels and hardware, and much more if you want thicker material. 

http://www.greenhousemegastore.com/product/16mm-polycarbonate-clear...

Now, another way, and much cheaper, is to cover with a two layers of 6 mil poly film, and inflate the airspace in between with a little blower. This is fantastic insulation, and gives the film a balloon type of rigidity so it doesn't flap like a luffing sail in the wind. I am building a GH right now, and my present thoughts are to go with single wall, corrugated poly-carbonate on the top surface of the rafters, and double inflated film on the underside of the rafters, giving me the durability of PC and the insulation of the double film. It's a bit more work than going with the triple wall panels above, but I'm hoping it will perform better and be cheaper.