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Temperature and Dissolved oxygen levels
http://byap.backyardmagazines.com/forum/viewtopic.php?f=1&t=3237		 Page 1 of 2
Author:  Chappo [ Apr 16th, '08, 00:46 ]
Post subject:  Temperature and Dissolved oxygen levels
It seems to me ,, from my reading , that these factors are the most ignored by the general population of Aquaponicers ( yes new word). I'd rather be a cer than a cist:)
i've read thousands of posts in hundreds of forums and hardly ever seen anyone quote their DO level. Near 99% of people are using air-stones ,, probably the single most ineffective way to add oxygen , especially in a medium less than 3 metres deep. There are several methods far superior to the air-stones but also short of the expense involved with pure oxygen injection.

Heating , is the other missing link. I read continually about fish going off their food , growing very slow etc and then hear temperature is often 8 degree C OR MORE below the species optimal temperature ,, note "optimal" . Yes SP will live perhaps even below 10 C ,, but growth/feeding ZERO. Also remember ,, your 'workers" , the algie are also happier above 20C.

The challenge here , in my opinion , is to achieve max DO levels and constant optimal temperatures with minimal cost.

Cheers
Author:  Dave Donley [ Apr 16th, '08, 00:56 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
Hi Chappo:

What aeration methods should we be using that would work better?

Note that some aeration is occurring through the flood and drain process of the growbeds - like a trickle tower. Also we look for ways of introducing waterfall effects wherever possible. For example, I get some bubbles where four loop siphons drain into the fish tank, and where the fish tank overflows into the sump, and where the water goes into the grow beds.
Author:  Chappo [ Apr 16th, '08, 01:25 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
The most efficient aeration systems in larger aquaculture / include the U-tube reactor , basically air bubbles are added to a tube that goes 20 odd metres under-ground ,, more pressure more oxygen exchange. Although efficient ,this method is impractacle in cost terms,for an average back-yard aquaponicer. There is also the ,AHHH forgotten the actuial terminology ,, but its when air is injected into a bell shaped chamber and the downward flow of the water equals the upward flow of the bubbles thus increasing contact time , therfore increasing exchange.
In my mind ,, whether I've taken my medication or not ( joke) the paddle wheel looks like a good option. It's very simple ,, widely used in Aquaculture etc etc. ( of cause a scled down model),
there is no need for the paddle wheel to actually be mounted inside the tank ,, I suggest a small version in a box on the return flow line. Oxygen levels at that point are lowest , therefore more easily added to.

Opinions / discussion / theories, most welcome.
Author:  Dave Donley [ Apr 16th, '08, 02:37 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
I think Charlie Little posted about the equalization chamber thingo before he bugged out. Sounds neat. Would be very similar to building a bead filter like what DDM has been doing.
Author:  Chappo [ Apr 16th, '08, 03:20 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
balancing the bell shaped container ,, the air flow ( up ) , water flow ( down) and the media , although ultimately efficient ,, may we ll prove to be a great pain the the behind.

I'm thinking a simple paddle wheel set-up in a box on the return line to the tank.

Thinking and proving thru testing are two different things ,, unfortunately mu dissolved oxygen meter is on my fish-farm in Thailand ,, and i won't be going back until Novemmber at the earliest:(

AHHH there's another thread to make ,, cheap dissolved oxygen meters from where?
Author:  jdphish [ Apr 16th, '08, 03:27 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
Chappo, I agree with you that DO levels aren't being measured by APers. I really don't believe DO is being ignored by APers. The economics of it are such that its not practical for most folks to have a DO, meter. And titration methods of checking DO are pricey as well. The simplest way to know if fish have enough DO is if they feed and aren't sucking air. I didn't say the best.

Probably the cheapest and simplest way to increase DO is with airstones and pumps. I didn't say the best or most efficient.

Quote:
The challenge here , in my opinion , is to achieve max DO levels and constant optimal temperatures with minimal cost.


I think airstones meets the above challenge best with the present technology. The optimal temperatures are a whole other matter. And I do understand the temp - dissolved gas relationships. Generally, its seems that folks with outside AP systems largely use indiginous fish. Therefore the fish live within normal temperature ranges, maybe not optimal for growth. Again, economics are a limiting factor for me and most other folks.

If cost weren't a factor, we might all have greenhouses, with pure oxygen contacter and one of these.........
http://www.aquaticeco.com/categories/Heaters/86/1/

Also, is this the type "bell shaped" thingy you meant-

http://www.aquaticeco.com/subcategories ... n-or-Ozone

I am sure better technology could be developed but we gotta use whats economical and available.
Like life, AP seems to be a balancing act.....we just do what works best for each individual.

Hope my opinion doesn't offend you. You have some wonderful ideas.
Author:  Dave Donley [ Apr 16th, '08, 03:32 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
+1 on the cones JD
Author:  Chappo [ Apr 16th, '08, 03:59 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
JD , love the reply ..... informative , non judgemental and most importantly accurate. Do you have time to give lessons to my wife ? :) PLEASE

Yes life and aquaponics are a constant balance of cost / benefit ratio.

The paddle wheel airator wil need to be judged on it initial , and on-going costs bbefore it could ever be deemed practacle. Also the Solar heat pump needs to be assesed on growth /output performance Vs costs.

Balance is the key to all things ..... forgotten who said it but he was bliking well right.
Author:  mrgrackletx [ Apr 16th, '08, 05:57 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
I've got a DO test kit. I don't remember it being that much more then any of the other test kits. Maybe it's completely inaccurate... I dunno. My system usually reads between 4-5 mg/l in the morning and 5-6 mg/l in the evenings. I tested the water in the Colorado river here in austin at the bottom side of a dam and it measured 10 mg/l O2.

I don't have much extra aeration set up. I think the enormous surface area of the growing media and the constant flood drains keeps everything going pretty well.
Author:  Jaymie [ Apr 16th, '08, 06:22 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
Quote:
AHHH there's another thread to make ,, cheap dissolved oxygen meters from where?


there are a couple of threads about this already

One thing with using air pumps to aerate the water, in many cases they are easier to convert/invert to 12V power in case of power outages, so I will stick with my air pump for now thanks ;)
Author:  EllKayBee [ Apr 16th, '08, 08:14 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
Yes - I disagree with the statement also:
Quote:
...these factors are the most ignored by the general population of Aquaponicers


Most of us have incorporated venturi type injectors to mix air with the water at several points throughout the water flow circle - may not be the most efficient way but is very cheap.

1)Water is bled off the outflow from the pump and mixed via venturi and returned straight back to the tank - continuous flow pump means continuous mixing.

2) Bell siphon with air tube - act as a venturi and sucks in air (only when GB is draining)

3) there are several more ways that are used in aerating the water and are constantly being stated on different threads which highlight the need for having some type of aeration method.

Air stones normally have been suggested as a power backup method or where some have wanted to switch off pumps during night hours (or as a temporary measure)

DO meters have been discussed but the limiting factor has been the cost and whether it is necessary at the stocking levels recommended - it has been been put on the "nice to have one list tho" :D


Interested in discussing the pros and cons of any method to BYAP use
Author:  RupertofOZ [ Apr 16th, '08, 12:02 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
Yep, economies of scale are what it's all about..... most peoples systems probably owe them about 5 years of fish and veges anyway.... :lol:

A paddlewheel in a box on the return line? .... hummm..... had kind of thought about something like this..... wonder if you could incorporate a "micro-hydro" generation to trickle charge a battery backup system.... to supplement a small solar cell....
Author:  gnash06 [ Apr 16th, '08, 14:06 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
I have two airstones connected in my system
1) In tank and running 24/7
2) In the top up water barrel running 24/7

I also have set up nozzles in the return line, when the sump pumps to main tank a heap of air is sucked through.
Can't ever see DO being a problem for me but would like to have the abiliy to test it :wink:
Author:  Chappo [ Apr 16th, '08, 18:55 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
Intersting replies , Rupert ,great thinking on the hydro trickle charge,,,why not use the same wheel and motor as a generator when its not being used for aeration,,,love it, costs may be the issue.
A couple of you have also said you would 'like" to be measuring the DO level but meters are soexpensive,.....,,welll,.....,,I wasn'tgoing to tell everyone but....I was watching a second hand DO meter on ebay and then forgot to bid :oops: it sold for $95.AHHHHHHHH.

I've started designing the unit,,,at work ( in my lunch break:),,but invisage a working model is months away.

Jayme,,,I'll make sure a 12 volt motor option is available.

Cheers
Author:  mrgrackletx [ Apr 16th, '08, 23:30 ]
Post subject:  Re: Temperature and Dissolved oxygen levels
what's wrong with these kits?

$8.99
http://pet-king.stores.yahoo.net/46798166306.html

or this?

$14.52
http://www.oceanproaquatics.com/shop/re ... -2216.html
(this is the one i use)
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