GaryD

Greenwater Aquaculture

322 posts in this topic

Hi, guys

Got my test kit from Amazon and did the test today, here are the results:

PH                   7.6

Hi-range PH    7.6

Ammonia         0 ppm

NO3                 0 ppm

NO2                 0

 

According to the booklet, these are good numbers (except PH, a bit too high), but Nitrates are low, maybe that's why my plants are not too happy. Possibly brown algae eats all the nutrients? 

Edited by curiousCat (see edit history)

Share this post


Link to post
Share on other sites

Gary, as always, thank you for the thoughtful response. I'll try to incorporate your ideas.

 

I tried growing azolla before, but it all turned red and died. Granted, that was when I did not have a shade cloth over the green house, so the water temps were in the 90's. Now, with the shade cloth the water stays around 80F. I'll try azolla again.

Share this post


Link to post
Share on other sites

Azolla has the ability to affix nitrogen.  80 degree water is still a little warm for azolla so don't be surprised if that turns red still. I did find that growing it on a little media such as sand or potting mix helps it grow when the others keep dying. I don't know why it helps, but am currently guessing that as moisture evaporates out of the soil and cools the media.

 

The yellowing is due to not enough nitrogen in the system.

Share this post


Link to post
Share on other sites

Guys, I am perplexed! Where is all the ammonia??

I cleaned all the filters, now the water is crystal clear, except for it's very red (but I did not add any iron to it).

Water is so clear, I can see far into the pool, to the bottom.

I added charcoal pouch, and oat straw (I think) to help kill algae.

 

All the above was done to, first to clear the water for the fish, and hopefully kill some of the algae.

 

The problem is, no plants growing! Gah! Duckweed just sits there for weeks, not growing. Water temperature is stable at around 80F.

 

I really want to grow duckweed in the tank for the fish. 

 

I did the test just today, Nitrates 0, Nitrats (sp?) 0. Ammonia 0. PH 7.5

 

HELP!

 

FishTank07092015_zpsphqo68ta.jpg

Share this post


Link to post
Share on other sites

Are you feeding the fish at all?   I can never grow duckweed in a tank if tilapia have access to it, they will eat it as fast as it can grow. I've read about red algae and wonder if that's what you have now.

 

Impressive filtration though!

Edited by Ravnis (see edit history)

Share this post


Link to post
Share on other sites

The reddish/brownish tinted water is likely due to the tannin content of the barley straw.

Share this post


Link to post
Share on other sites

Hi

 

I added charcoal pouch, and oat straw (I think) to help kill algae.

 

The reddish/brownish tinted water is likely due to the tannin content of the barley straw.

 

Agree on the tanin content in the straws is a likely cause, but he did say oat straw ? rather than barley straw, wich made me curious I never heard of oats used as such ?

 

cheers

Share this post


Link to post
Share on other sites

The reddish/brownish tinted water is likely due to the tannin content of the barley straw.

No, sorry, the red color started way before the barley. I added the barley thinking it would clear it, but no such luck.

Share this post


Link to post
Share on other sites

Are you feeding the fish at all?   I can never grow duckweed in a tank if tilapia have access to it, they will eat it as fast as it can grow. I've read about red algae and wonder if that's what you have now.

 

Impressive filtration though!

Oh heck yeah, I 'm feeding the fish. Twice a day, "Trophy Fish" pellets ($$), for as much as they can eat within 5 minutes.

They don't have access to duckweed because it's contained inside the floating trays. Maybe they are jumping into the trays, I dunno. Would not run that past them though. 

Share this post


Link to post
Share on other sites

Hi

 

 

 

Agree on the tanin content in the straws is a likely cause, but he did say oat straw ? rather than barley straw, wich made me curious I never heard of oats used as such ?

 

cheers

That probably was barley straw. My bad.

Share this post


Link to post
Share on other sites

But guys, the red does not bother me as much, as why is there no ammonia? Maybe bacteria in the bio filters eats it all? Mind boggling. Fish poop like crazy.

Share this post


Link to post
Share on other sites

Depending on the amount of duckweed you have, it is likely taking up ammonia/ammonium directly. It does this quite well. Algae will take up a lot of nitrogen as well.

You might want to try growing duckweed in a separate system to get it started. A little all-purpose garden fertilizer will make it perfectly happy. Once you've got a good batch growing you could start transitioning some into your AP/RAS system.

Share this post


Link to post
Share on other sites

OK! Got my duckweed farm started. It is literally compost tea. I took a shovel full of compost into a 5 gallon bucket, and brewed it in the sun for two days. Then filled these trays and added just a bit of duckweed to each. I also tested it, it is 8 ppm ammonia, probably more, but 8 ppm was the highest test strip allowed. We'll see how this goes. Or else I'll be growing mosquitoes, if all fails,  :lol:

 

I used aluminum all-purpose roasting pans ($2 at the dollar store) because they are shallow and have large surface area. Don't know if I'll have an issue with aluminum leaching into the duckweed. If anyone has any insight, I'd appreciate it. I'll keep you guys updated how this project goes.

 

On another note, I have little tilapia babies now. I saw a batch of them a few weeks ago, but then they disappeared after a few days. I guess large tilapia ate them.  :( So, this time, I caught as many as I could, and now they are living in the house, with the humans. They are so tiny! I'm glad that my tilapia is breeding, after all that was the whole point, to have a self-reproducing food source.

 

Here's my duckweed farm:

 

duckweed%20in%20trays_zps8gpmkysi.jpg

neighbor likes this

Share this post


Link to post
Share on other sites

Hey, all!

 

Another update.

 

Four days ago I replaced 3/4 of the water in the pool, as well as vacuumed the pool bottom. There was a lot of crud on the bottom, including oak leaves; that's what probably gave the tannin's and made the water red. Now the water is crystal clear again, and starting to green up. Oh, well, it's a greenwater aquaculture after all.

 

I want the fish to live in super clean water before I start eating them. After 8 months or so they don't grow very much, so the feed is wasted. But I cannot feed too much because then filtration will not be able to deal with it. So, in a month, freezer time, baby! 

 

It looks like there is way more in the pool than the original two hundred, minus a few casualties. They have been breeding, and some of their offspring even survived by some miracle. I raised around 50 of the babies to about an inch and a half in two months, then released them back to the pool. In a few days there were less than ten left. Bastards ate them! 

 

Still could not find any lab that tests food for the consumer, only for the companies. So, I'll have to take the chance, I guess. Thinking if fish lives in clean water it must be healthy, or at least that's my expectation.

 

8da8bad9-4dc6-45ab-80e4-54177f536dc1_zps

 

Share this post


Link to post
Share on other sites

Thanks for the update, CC.....keep 'em coming.  We need more sustainable fish production solutions.

 

Gary

Share this post


Link to post
Share on other sites

First harvest!!

 

fishHarvest_zpsivyso9uq.jpg

 

fishHarvest2_zpscstximi4.jpg

 

 

What grossed me out though, even when the head was severed from the body, it kept breathing. I did use the sharp filet knife to drive it through the brain, but either it's reflexive, or it was still alive when I cut the head off, dunno. Would prefer not to deal with this. Ah, well. Fish dinner tonight! :)

Share this post


Link to post
Share on other sites

First harvest!!

 

What grossed me out though, even when the head was severed from the body, it kept breathing. I did use the sharp filet knife to drive it through the brain, but either it's reflexive, or it was still alive when I cut the head off, dunno. Would prefer not to deal with this. Ah, well. Fish dinner tonight! :)

Had the same thing happen to me on my first fish, didn't like it too. When I'd go fishing years ago, the head would usually go straight into a pelican's mouth, never thought of it more until the first harvest. I've tried spiking the brain and with practice I hope it may be a faster way.

curiousCat likes this

Share this post


Link to post
Share on other sites

Had the same thing happen to me on my first fish, didn't like it too. When I'd go fishing years ago, the head would usually go straight into a pelican's mouth, never thought of it more until the first harvest. I've tried spiking the brain and with practice I hope it may be a faster way.

 

What do you use to spike the brain with, Rotaco?

Share this post


Link to post
Share on other sites

What do you use to spike the brain with, Rotaco?

A very sharp skewer as 1st choice. I've also used a knife but I don't like it as much as a fine sharp metal skewer.

I saw the concept on a RobBob blog, described as ikijime or spiking.

This site gives a good guide to the fish (around here), and usually supplies a picture of the target and fish type.

http://www.ikijime.com/fish/

 

I think I should get some mesh gloves for this technique, because I've had a close shave with the knife on the hand.

Share this post


Link to post
Share on other sites

Hey, guys, just an update.

 

Large fish is doing OK, especially on the skillet. :) They are multiplying, so here's my hobo grow out tank setup, made out of a storage tote and a garbage can.

 

I will be re-doing filtration system for the large system to encompass a 3 inch pipe in order to fit a larger pump. I am not happy how quickly the water gets dirty. Will update on that too.

 

GrowOutFish_zps9lsmmyln.jpg

Share this post


Link to post
Share on other sites

Another day, another harvest ....

 

It came to a point where no matter what I did, I could not keep the water in the "tank" clean. There was just too many grown fish there. It was time for some major thinning of the herd.

 

I drained most of the water and scooped them out using a landing net. Then, it took me over 7 hours to process all this fish. All in all, 96 fish, and a bit over 48 pounds.

That's not the first harvest. And this whole thing started with 200 fingerlings last August. So, considering the fingerlings were 2 months old when I purchased them, the largest fish, males, are about a year and a half old, and weight around half a pound. Smaller ones, and females, are less than that in weight.

 

48 pounds of fish. This is still mind boggling to me.

 

Hope you guys enjoy this picture of the delightfully bountiful harvest:

 

NinetySixFish_zpsvx957s75.jpg

Edited by curiousCat (see edit history)
ande and Ravnis like this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now