Backyard Aquaponics
A place to discuss aquaponics

thanks Gary and steve

gary duckweed sounds a great idea but the big question is will it grow in full sun? it is fairly hot here in summer and the pond is too big to shade ........

we already tried another type of weed but cant remember its name ....... it floats on the surface like duckweed and is supposed to double its size every 24 hours ....... ours turned brown and slowy died without ever getting any bigger

steve the lead tester is very interesting .......

I was unsure what else was used a desalinators ( brain fog )but now you say it probably was distillation

frosty

bump for gary ..........

I am very interested in growing duckweed but is there any species that will grow in the sun ?

frosty

From what I know, duckweed should be fine growing in full sun, infact that is where you get your ultimate poroduction, in full sun... Gary would have to confirm for sure though....

Hi Frosty

Duckweed grows pretty much everywhere, it seems.

The problem that we've experienced with full sun related to the size of the container we were growing it in (the water just got too hot) rather than the fact that is was in full sun.

A species of duckweed which is native to Australia (Lemna Wolffia) grows in far North Queensland and it doesn't get much more full sun than that.

The more likely issue that you'll have in a big pond is wind. Wind will push the duckweed up against the sides of the pond where it virtually mulches itself out of existence. I've seen photos of where large duckweed producers install little floating pens into larger bodies of water to offset this problem. See http://www.duckweed.com.au/

In any case, the best thing would be to try it. I'd buy a packet from the aquarium shop and breed it up in some small (than your pond) containers to get some mass going and then put it into the pond. It will quickly become obvious if it works - you'll have duckweed coming out of your ears.

thanks Joel and Gary

we will try it ........ is now a good time to "plant" ?

although as hubby says our sun is much stronger than in the tropics like north qld ........ something about moisture in the air ..........

we do also have a lot of wind but that is easier to solve with a shadecloth windbreak round the pond

frosty

regarding Frosty's comment:


just how old would that PVC be??? any way to tell??? I have a few pvc pipe I gathered from a number of places which I intend to use and I want to make sure that they are safe and dont make my fish sick

I wouldn't be as worried for the fish as i would be for myself! We are going to eventually eat them so the lead will be passed up the food chain

I cant believe aquariums still weight down their aquatic plants they sell with lead ties. I remove them as soon as i buy them, as i always use my water change water from my aquariums on the herbs.

I used to do the same with the lead... But then again my big tank produce so much plant material that I have not bought aquatic plants in over a year (instead I gave a whole bunch away)

As did mine I used to thin the water wysteria down to 1/4 of the tank each month, and by next month it had grown to 3/4 of the tank

Curious thing, i had one white tube and one purple growlux tube. since i changed light fittings and only had one normal white light i got ZERO growth. I have since installed another purple tube (about 1 week) and i'm already noticing new growth.

I know about the differnet light spectrum requirements of plants, but such a difference? I was surprised.

Steve

I have 3 growlux lights going in my tank - which is $75 to replace every 8 months (they tend to become less effective after about 8 months for some reason)... I need that many to penetrate to the depth of just over one meter effectively.

why not just go for a 150W metal halide? Lighting is a whole nother topic, but just quickly........... If i remember corrrectly there is intensity and penetration (probably not correct terms) MH has much better penetration to start with, higher efficieny and the tubes probably worth the same as 3 grow lux. Am i right with the pentration thing? Was a long time ago that i read up on lighting

never used MH before - does it emit the same light spectrum as the growlux?

AM,

growlight tubes have two sharp spectra peaks, one in the red and one in the blue, giving them their caracteristic purple look. These two spectra are the only two that plants really utilize. Good for plants but if they are the only tubes you have the aquarium will look very dim, that why a cool white tube is usually added.

Cool white tubes have a very shitty spectrum spread.

Metal halide tubes which form prat of the High Intensity Discharge (HID) family by nature have a "daylight" spectrum spread, including the two bands used for photosynthesis. They are the closest to sunlight you can get, and are very intense so you get good penetration.

These are the light fixtures you see at aquariums above plant tanks.
They are also the most efficient lighting in lux per watt

They require a special transformer and the best colour temperature for growing plants is around the 5000 Kelvin mark. much higher colour temperature tubes have been developed, but their uses is almost exclusivly for marine aquariums as their colour is shifted way into the blue / UV spectrum.

They are generally quite expensive initially to buy, but there are many sources of bargains. The recycle place up the road from me had a box of complete lamps and transformers for $50 each and the tubes were 5400K!

Damn, i was meaning to go back and buy 5 of them, they're proably all gone now

read up on the links below

http://futuregarden.com/lighting/choosi ... ights.html

http://www.geocities.com/ptimlin/lighting.html

Oh yeh, they run VERY hot, the inner quartz envelope glows brigh organge for over 30 seconds after you have turned the power off! Also, if you get one, don't freak if you trun it off and then it won't light again. They need to cool down before the arc will establish again, has to do with the high internal pressure when hot. They also take upto 5 minutes to warm up and produce good light.

PS: i might move this and the last few messages into a new topic called lighting in a few days if that ok

Sounds like a good plan Steve.... Nice work on the lighting info guys...

I am sure my father used the same thing in the security lighting around where he used to work - they bling you if you look at them and they were almost egg/rugby ball shaped in south africa... and I remember them glowing red/orange for ages afterwards... (he installed one at home on a motion sensor and if you were quick you got past it before it lit up properly)
I will look into it... but I may have to redesign the hood of my big aquarium if it produces so much heat - the thin timber would not do too well - perhaps I should look into other materials such as cemet board...???