Newbie questions

[Peter H.]

Hello,

 

I've tilapia (mossambicus) growing in a ~30 gallon barrell for about 4 months now and would like to start a small (12"x23"12") grow bed using hydroton as media.

 

This site, especially the 'Rules of Thumb', is immensely helpful, but some questions remain:

1. In the discussions regarding water pumps, commenters expressed concern that the pump should be behind a filter or screen so that solids (fish waste) do not get sucked in.  My impression is that it is desirable for solid fish waste to be transferred from the fish tank to the grow bed where bacteria and worms break it down.  What am I missing?
2. The 'Rules of Thumb' mentions adding Maxicrop Liquid Seaweed to the system.  Will this harm the tilapia?  Should this be added to the fish tank or grow bed?
3. Loop siphons seem easier to implement than bell siphons.  Is this correct?
4. Are the worms a certain type, or can I use the ones found in the backyard?
5. What are the easier vegetables to get my feet wet (was planning to try lettuce, basil and mint)?
6. What method is recommended for growing from seed?  I was planning to sprout in 1" net pots using hydroton, then bury the net pots (with sprouts) in the grow bed media (also hydroton).

Thank you.

 

-Peter.

[Chi Ma]

I can only answer point 1 and 6 from my own experience.

 

1. In the discussions regarding water pumps, commenters expressed concern that the pump should be behind a filter or screen so that solids (fish waste) do not get sucked in.  My impression is that it is desirable for solid fish waste to be transferred from the fish tank to the grow bed where bacteria and worms break it down.  What am I missing? I use a screen/pre-filter so that large debris or fish are protected from clogging up the intake.
2. What method is recommended for growing from seed?  I was planning to sprout in 1" net pots using hydroton, then bury the net pots (with sprouts) in the grow bed media (also hydroton). I start my seeds between sheets of wet news paper put somewhere warm. As soon as they sprout I transfer them to my net pots filled with Hydroton.

 

 

[TCLynx]

Hay there.

 

1- Well you don't want your fish or object that can get jammed and stop the pump to get sucked into the pump but yes you want the fish poo to be sucked out.  So something more like a coarse grill small enough to stop fish and leaves from getting into your pump but open enough to let the poo through is a good choice.

 

2-Maxicrop (so long as it is the original 0.1-0-1, is safe for fish but you don't need too much, a spoon full per week would probably be way more than enough for your little grow bed.  I do hope you don't have many fish in that barrel.  I usually add to the grow bed but even if added to the fish tank, it will circulate around everywhere, it will turn your water dark for a little while though.

 

3-depends on the materials you have to work with.  Loop siphons are pretty easy to adjust the height but afnan bell siphons are a little easier to get working with wider flow rates.

 

4-any type of composting worms work, if the ones in the backyard are big earthworms, they might not be as good but if they are ones found in wet piles of leaves, they are probably perfect.

 

5-most veggies do well.  Mint might take over your little grow bed though.  Lettuce is good in cooler weather basil in warm weather.  Carrots, turnips, beets, chard broccoli all work too for cool weather.

 

6-I wouldn't bother with the extra expense of net pots in a media filled grow bed.  You can simply start seeds right in the bed.  Most of the time I just sprinkle them around or you might use some paper towel or cotton ball to create a wick (to hold and keep moist) for extra small seeds to keep them from floating away in the flood cycle.

[Sylvia Bernstein]

Peter, these guys are giving you great advice.  The only thing I would add is that the reference to adding Maxicrop was for system cycling; to help establish your beds and your plants.  After you are fully cycled, and you keep pH in the 6.8 - 7.0 range you actually shouldn't need to add anything else to your system but a high-quality complete fish feed.

[Peter H.]

Thank you all for your guidance.

 

Addressing TCLynx's concerns about the number of fish in the barrell (no pun intended):

I had purchased 12 tilapia of varying maturity from Tilapia Mamma in San Diego along with a 55 gallon food grade barrell and a roll of plastic (PVC?) mesh she recommended as a matrix for bacterial growth in August.  I lost one fish earlier on; the body seemed to have had a bite taken out of it.  I lost another this weekend; found it floating when I went to change the water.  They are difficult to count because the barrell is deep (I need a light in there), but I think only about 4 are left so I'm leaving the water level at about ~30 gallons to give room for rainfall which we're having a lot of lately.  I believe that because I had different size tilapia, the larger ones may have, sadly, eaten the smaller ones.  The strange thing is, I would expect to see fish bones, but I don't.  I plan to purchase 5 more tilapia in the spring and grow them to maturity in an aquarium before adding them to the system.

 

If I were to buy goldfish or koi, do I need to quarantine them before adding to the tilapia?  If I understand correctly, quarantine is to prevent the spread of diseases from new fish to exiting fish?  Other than strange growths or going belly up, how do I tell if an aquarium bought fish is safe to add to the existing tilapia?

 

Chi Ma,

You recommended [e-mail] for tilapia in SoCal.
Does he sell in low quantities (<10) and where is he located?

 

Thank you all much for your help.

[Chi Ma]

He is in Riverside. Drop him a line. He's nice. Packs the fish well for shipping and full of info. Tell him I sent ya.

Peter H. said:

Chi Ma,

You recommended [e-mail] for tilapia in SoCal.
Does he sell in low quantities (<10) and where is he located?

 

Thank you all much for your help.

[TCLynx]

Well personally in 30 gallons of fish tank, I probably wouldn't want much more than about 6 tilapia.

 

And I don't know what sort of filtration you have (what do your water test for pH ammonia, nitrite and nitrate show?) but flood and drain gravel beds on their own, a nice recommended stocking density would be one fish per cubic food of flood and drain media bed. 

 

Quarantine is really just to make sure you don't have ich or something else obvious show up during six weeks or so you keep the fish in an isolated system.  Trick is you need a cycled up system to quarantine the fish in.  If nothing obvious shows up in the quarantine period then the fish are probably safe to put in with the general population.

[Peter H.]

I don't currently have mechanical filtration, only biofitration.

I do a ~30% water change every two weeks.  This keeps my ammonia at ~0.25ppm, nitrite at <0.5ppm, nitrate at <40ppm.

I wonder if the nitrate level is too low for planting?

TCLynx said:

Well personally in 30 gallons of fish tank, I probably wouldn't want much more than about 6 tilapia.

 

And I don't know what sort of filtration you have (what do your water test for pH ammonia, nitrite and nitrate show?) but flood and drain gravel beds on their own, a nice recommended stocking density would be one fish per cubic food of flood and drain media bed. 

 

Quarantine is really just to make sure you don't have ich or something else obvious show up during six weeks or so you keep the fish in an isolated system.  Trick is you need a cycled up system to quarantine the fish in.  If nothing obvious shows up in the quarantine period then the fish are probably safe to put in with the general population.

[Chi Ma]

If you need a little help controlling your nitrates, throw in some water hyacinth. It will soak up some of the nutrients while your grow beds cycle.

[TCLynx]

Get that grow bed hooked up asap, 40 ppm of nitrate is plenty for planting (especially such a tiny grow bed).  I would say get lots more filtration/grow beds on there so you won't have to worry about those ammonia and nitrite readings.  I'm used to those being 0 and 0.

[B. Pearcy]

Is there any kind of taboo that prevents the blue aquaculture beds like the ones sold by these folks being a good idea?  http://www.aquaticeco.com/subcategories/3114/Rectangular-Polyethyle...

 

and coupling them with tanks like this one:

http://www.aquaticeco.com/subcategories/955/Round-Polyethylene-Tank...

 

or this one:

http://www.aquaticeco.com/subcategories/939/Polyethylene-Tanks-Blac...

 

I notice most of the blue ones say "FDA approved materials" while the recycled black ones do not but just "recycled polyethylene".  Should that be concerning?

[TCLynx]

They would work fine.  Just most people who want to do DIY aquaponics are rarely wanting to spend that much for the grow beds but they would work just fine.

[Nick LaHaise]

Quick newbie question -

 

I'm in the process of building a bathtub aquaponics system and I'm wondering if I want the top tub (grow bed) to be level or if I want it to slant towards the drain where the auto siphon is?

 

Thanks for the help!