Backyard Aquaponics
A place to discuss aquaponics

Compost specially for tilapia.....

Or you could feed them Moringa...

Sweet potato leaves are a favorite of my tilapia. Sweet potatoes are a close relation to morning glories.

TC...Didn't know that. Interesting. Love growing Morning Glories for the abundance of tumbling flowers.

No leaves in winter ROZ. Great for summer though.

Chappo told me his tilapia farms in Thailand ate algae. They drop bags of urea into the water then observe the algae. When they get the right color of algae they raise the urea bags out of the water.

Everyone keeps saying to avoid algae, but it seems to me that its done every day commercially. I like the idea if dropping cow poop in the water to grow algae. Last year I had one fish in a tank with algae. It grew better than the fish on commercial feed. It did however die when temps got over 38C.

In large pond culture, algae is a standard method of feeding the fish, however, in recirculating tank culture, algae can be trickier since pH swings and crashes can take out a whole system far more quickly.

Would be nice to feed algae in AP but we still need to figure out how to handle it in order to keep things healthy and avoid the crash.

This might be a case of who is gonna take one for the team and risk a system to algae blooms to see how to make it work for recirculating AP.

There is one issue though, many of us have noticed that after the initial algae bloom when getting a system going, later once there is dead algae decomposing in the grow beds, it seems to keep the algae down through the system. Kinda natural algae control so one would need to figure out how to overcome that.

It certainly makes the best economic sense. I should try it in my current pond.

Interesting how that one fish grew better.

I also like the idea of using animal dung. And it creates a living larder. Minimum maintnance too. And I read algae is the perfect food along with the zooplankton that also flourish with the dung fertilization.

What kind of fish was it DDM? You think it died from temp or some sudden extreme DO deprivation due to the heat and the algae?

Makes sense. I think it was you TC that posted that really interesting article that proposed how it was that algae died. I saved it.....

He explained that heterotroph bacteria consumed dead organic matter... a proces more commonly known as plain old rotting. Same bacteria in a compost heap.

Earlier in the article he also explained that Liebig's Law of the Minimum states that "growth proceeds only as rapidly as the least available necessity of life allows." If we can remove or reduce one or more of the required items, algae cannot flourish. So for algae to flourish do not do this. If his theory is correct then regular soaking of dung in bags could keep algae from complete die off. In fact in continual algae bloom cycles. This is supposed to be done late morning for best results the article I posted above stated.

Regarding pH swings...

I read the following here...http://www.geocities.com/tokyo/4468/algae.html


As you say... need to keep that from a radical swing within an AP system. I know that tilapia tolerate hard water... alkaline water. So might be the fish to use... besides their well-known ability to filter out algae in water.

Perhaps size of tank alone could buffer this cycle from going into a complete crash? If the system is not large enough to offer this buffer then could something be added slowly through the night to combat this? The obvious thought is DO to be increased mechanically through the night. My inexperience here might be making my guesses way out. What do you think?

The other challenge would be to stop the algae clogging the pump in a recirculating system such as AP I would think ..... so some primary filtration section might be necessary before the water to be pumped gets to the pump. Not too hard to design. Even a basket with stones or what ever could be placed before the pump. Lifted and washed with a power hose once a week or whatever. A bit more trouble but not too labour intensive for the economic gains. Again what do you think?

Algael bloom management and micro-organism succession are the basics of pond based aquaculture. Nutrient decomposition is a natural process that occurs within the pond and can only be controlled / influenced by feed rates and bloom management techniques.

Do management is critical and needs to be thoroughly understood and constantly monitored.

Such techniques, with their associated swings in pH and DO are managable in large water bodies... but within a small margin of error...

It is extremely difficult to manage these factors in small volume recirc tank systems and the margin for error is correspondingly smaller, the swings proportionally larger and the time window for intervention so small as to effectively require immediate response.

To do so would require constant 24/7 monitoring and supervision... and regular intervention in feed rate application and equipment maintenance.... to the point where it is essentially unviable (economically) and too time consuming to make it an acceptable practise.

I tend to agree that in a small volume system, managing the algae would be hard.

The idea that occurs to me is to have an algae-tank that is valved into the FT. So you have an open-sun tank with whatever fertilizer you want to grow as much algae as you want. Then when you need to feed the fish, dump however much algae-water into it. The FT is covered/low-light, so the algae will not survive very long.

When the tank is clear again, add some more.

You would need to be extremely aware of the relative DO levels in both tanks... and volumes

i.e. ... if you were to add 50% of the volume of your tank water from the algae tank... early morning... you could end up throwing in a volume of low DO water from the algae tank... into a tank which in itself may already be low DO....

Every micro=organism within your fish tank ..... will consume oxygen....

You may also be introducing pathogens from the algae tank... unless it was kept sterile...

Personally... if the reason is to supplement feed... I think you'd be better off drying the algae... and/or just feeding dried spirulina....

Traditional Japanese Ranchu breeders raise their fish in controlled levels of green water, which they feel is essential to proper wen (head growth) development. In Chinese, the character for algae is part of the term for goldfish health. Algae is a good thing as long as it is controlled it would seem. The economic benefits make this worth pursuing.

Not such a secret science. Gasping tilapia... the only fish I would use along with carp in such a venture... would quickly educate the need to certain adjustments within a specific system. Constant monitoring would only be initially.

Agreed. As was discussed earlier on this page. Need the larger system as a buffer.

Definitely at first ROO. But not once required management understood. I think the economic benefits outweigh these initial challenges. The Asians have been doing this for hundreds of years for good reason. Worth paying attention to what they are doing.

Your comments interested me Tamo. They got me thinking. Isolate the problem....

I would want to leave the fish swimming in this green "soup". This has been successfully done for so long now in Asia that it makes a good starting point. The diffculties seem to rise when this system is attached to an AP system. Fingerlings need this rich nourishment and so perhaps when fish-raising is important as the product, the most economic way to raise them is outside of AP. A selection of large grown fish could then be chosen for the AP system and feed could be stuff raised on the farm. This works economically too. Keep the dung for the growing algae and zooplankton for the young fish and use Moringa, mulberry, bugs (underwater light)....etc for the poop production fish pond used to feed the plants (AP). I would insert gates to aid in sweeping up the fry at intervals and transfering them to the grow-out tanks.

Regarding DO levels. Far less problematic in fish grow-out ponds as the Asians do. They don't seem to be sweating it. Going to look further into what they say. Oxygenation at night via flow-forms and waterfalls might be a simple solution.

Anyone know anything about this? Maybe something worth investigating.....

Colloidal Silver is an algaecide........
http://www.tps.com.au/pools/algae.htm

Effect on fish.......
http://www.csfacts.com/pages/pfish.html