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I've been doing some research about alternative feed. some studies show duckweed; I think that Moringa Oleifera  leaves are the best.The leaves are very rich with a balance diet, It's a tree that grows in tropical and subtropical climate easy to maintain and within 6 Months of planting  you can start harvesting the leaves.

I would like to hear your thought in that one.

Afraitane.  

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i don't see any more talk on duckweed? anyone tried it? or something else? I have goldfish and I hear that they overfeed on it if you grow it on the top of the tank- I was thinking of growing it on the top of a sump tank?

 

many people grow duckweed and many people get high hopes about it when they first read about it.  The truth is, to grow enough of it to significantly replace commercial feed, you need a huge surface area of calm water and lots of nutrients.  Sump tanks tend to have fluctuating water levels and splashing which tend to splash the duckweed up onto the sides where it dries out.  Duckweed also uses ammonia directly and I've found it grows best in dirty water but calm dirty water also tends to settle out solids which can turn into a really nasty anaerobic mess which is not a good thin in an aquaponics system.

 

This can be made to work but there are challenges to it and it isn't the miracle of free fish food that some people make it out to be.  The high protein % quoted to weight is actually for dried duckweed and fresh duckweed is mostly water.

 

All that said, it can be a useful feed supplement as can Black Soldier Fly larva and worms and the bugs that fall from a bug light or bug zapper but they are generally all just supplements so far for most people.

thanks TCLynx. This is really helpful. Are there any miracle plants, or any other plants people have tried?  Trying to close the loop- a little leery of the BSF larvae thing in my classroom- though I do have composting going in the corner-  I mean- I could be convinced- I just have to research and see how the harvesting works, right? Thanks again, R

Well For BSF to work you need the flies to come lay eggs in your bin and that isn't likely to happen indoors and I think you may be a bit far North for them anyway unless it's possible to get a stable population surviving in a large greenhouse or something.

 

There are no single "miracles plants" as nature is far more complex than that.  Now if you are talking aquarium scale systems, you may be able to have a bin off to the side that will produce a fair amount of duckweed for your fish that you give a hand full or so to them each day.  Duckweed is also a great ammonia sink as in if you have a system that doesn't have enough filtration or plants, if you add a duckweed bin it can help take up the slack or at least use up some of the excess ammonia.

 

I don't know if watercress is of much use as fish feed but it certainly uses up lots of nutrients during winter down here and will probably thrive year round in a cooler or indoor situation.  It also likes higher pH so is great for any system that struggles with high nutrients because of high pH.

 

There are some other things that I've heard of people touting as miracles (actually more for feeding people than fish) one is spirulina the algae though growing and processing that can be labor intensive but might be an interesting project for students of the right age.  I'm sure you can find some info on that by internet search.  And then there is Moringa, but that is more of a subtropical tree so perhaps not appropriate to a classroom at least not till you get a greenhouse space to work with .  Then there are mulberry leaves which can be fodder for many ani...

 

I'm hoping to try growing some cherry shrimp as feed supplement for my fish sometime soon.

Thank you for the plant references. I drink spirulina in the morning! How cool. I imagine fish eating it would be much healthier.. I will look for a source to buy the water cress..

On a side note, I saw this DIY feeder that the folks at Garden Pool built- it seems pretty cool:

http://gardenpool.org/?cat=4

The other tricky thing is I have on the bottom of the aquarium a mineral-high substrate that I planted live plants in and added gravel to maybe two days late ( the water was looking pretty cloudy and then starting to get murky). The second tank that I started, I put the gravel in right away and it is crystal clear ( no fish yet) also the pH seems to be hovering around 6.5-7.(so the watercress might be a really good idea)  I haven't put the fish in yet, hoping that the tap water I kept adding would help clarify the water. Clearly, from the forums I am learning this is a bad idea for pH balance. I am wondering how often I can add 10% water (once a week?)  I also was trying to think of ways to cut down on the evaporation. The aquariums are covered on 3 sides.  Any suggestions?

When you add veggie plants, they are going to suck up and transpire water so there is no way to avoid topping up the water.

The fish and bacteria like the pH above 7, it is only the plants that really want it lower.  The biggest worry about adding water is if your water is treated with chlorine or chloramine.  In a new system you need to neutralize these but I'm not a good resource about what water conditioners are food safe since I have well water.  Once a system is well cycled up, you can do up to 10% water top ups with treated water and usually be ok but I would say topping up more often with less water is better in such situations.

As to the tap water bringing the pH up, 6.5-7 isn't high (provided that is the outgassed reading, tap water directly from the faucet will give false low pH readings but if you leave it to air out for a while you will get a higher pH reading.

In the tropic i have lots unwanted bugs and other insect. Does anyone know an easy way how to catch those and feed them to my fish. Like something sticky (molasses?) and soluble that will not harm the fish...anyone?

I've used bug zappers over my tanks and there are bug lights that spin a little whip below a light to know bugs into the water.  Or I've heard of people using a combo of a light and a fan to knock bugs into the water.
hmm ok. so it would be useful to have a reserve of water that had been primed for the tank and to add every 2-3 days, but with less than a 10% amount of water- i'll try filling an empty aquarium tank that is exposed to sun and a bubbler? it seems the chemicals people add to deal with chlorine and chloramide are not a sustainable solution?..

TCLynx said:

When you add veggie plants, they are going to suck up and transpire water so there is no way to avoid topping up the water.

The fish and bacteria like the pH above 7, it is only the plants that really want it lower.  The biggest worry about adding water is if your water is treated with chlorine or chloramine.  In a new system you need to neutralize these but I'm not a good resource about what water conditioners are food safe since I have well water.  Once a system is well cycled up, you can do up to 10% water top ups with treated water and usually be ok but I would say topping up more often with less water is better in such situations.

As to the tap water bringing the pH up, 6.5-7 isn't high (provided that is the outgassed reading, tap water directly from the faucet will give false low pH readings but if you leave it to air out for a while you will get a higher pH reading.

There is at least one food safe chlorine/chloramine neutralizer but I don't know which one that is off hand since I've never had to buy it.

 

If your water is only treated with chlorine then the spare aquarium, bin, barrel or large bucket with a bubbler can take care of the chlorine given a few days.

 

If your water is treated with chloramine, you may be better off filtering it out since it takes more like three weeks to have much effect at outgassing it.

thanks TCLynx!

 

Chloramine can be removed from tap water by treatment with superchlorination (10 ppm or more of free chlorine, such as from a dose of sodium hypochlorite bleach or pool sanitizer) while maintaining a pH of about 7 (such as from a dose of hydrochloric acid). Hypochlorous acid from the free chlorine strips the ammonia from the chloramine, and the ammonia outgasses from the surface of the bulk water. This process takes about 24 hours for normal tap water concentrations of a few ppm of chloramine. Residual free chlorine can then be removed by exposure to bright sunlight for about 4 hours.

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