The Thailand expat forum for Travel, Lifestyle and Fun.

mellow

^ I'm not familiar with loop siphons. The water needs to move at a pretty good clip in an RAS. The water in the system needs to go though the filters ( recirculated) every couple of hours or so, a topic of much discussion. That loop may be quite a slowing factor. I did see a loop siphon on a link one time, where they used it to get a better constant flow however. Much larger pipe or hose used in that loop and used for a different purpose. Contact time is also a debate, many say the bacteria do the job upon contact. There are some who believe that by recirculating some of the water back into the biofilter it multiplies the effect of the process. If the filter is packed with media and is flouded, air has to be pumped in and the media aggitated, or else you just have a basic filter chamber with filtering material in it. A lot will depend on the stocking rate, having a few fish, enought for the plants to grow and to also use as dinner, as compared to raising fish for sale.I suppose one has to decide upon a balance of what works best for you, and the system your making. Is that an embossed radiation stamp on that blue barrel?

mellow

An overview on sizing a biofilter:
BIOLOGICAL FILTERS FOR AQUACULTURE

tsicar

interesting system. where is the media though.
i assume that the media is alternately in contact with air and then with the water, as in a R.B.C?
has anybody looked up "rotating biological contactors"?
media is rotated very slowly so that the bacteria is in contact with air for half the cycle, then in contact with the water for the other half cycle. i only saw commercial designs and products available over the internet, very expensive, and using a system of removable discs as media. but i am sure that if you find some old roadsweeper brushes, they could be rotated by paddlewheel from your input water(free energy.)
huge surface area from these, and the bacteria get plenty of oxygen, plus they can be attatched to floats and anaerobic processes happening beneath them in the same tank, without clogging the brushes with solids.

Smithson

^ Thanks for that, from what you've written doesn't seem like they would have much place in aquaculture.

BTW, that's not my system, just a pic of the internet. Dunno about the radiation logo, but I doubt the hose is food safe.

tsicar

why not? it seems like the most energy efficient system there is.
i will try find a link somewhere, but i seem to remember they were being used in aquaculture, even being used (ilthough i personally would not recommend), inside the rearing tanks!! seems like a really good way to get the most oxygen to the bacteria at the lowest cost.

here's something i just found that explains the process a bit.
i know it is not a commonly used system in aquaculture, mostly being used in large sewage treatment plants, but it IS a biofilter, and if it can treat sewage, it should be able to be used in aquaculture.

Rotating Biological Contactor (RBC) Process



As an efficient fixed film wastewater treatment technology, Rotating Biological Contactors are well suited for secondary and/or advanced treatment in municipal or industrial applications. The long-term reliability of this process is evident in the more than 6,000 units operating today.







The RBC process consists of a large disc with radial and concentric passages slowly rotating in a concrete tank. During the rotation, about 40 percent of the media surface area is in the wastewater. The rotation and subsequent exposure to oxygen allows organisms to multiply and form a thin layer of biomass. This large, active population causes the biological degradation of organic pollutants. Excess biomass shears off at a steady rate and is then carried through the RBC system for removal in a clarifier.
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the concept and design of this system intrigues me, and i definitely want to try out a modified version that is stuck somewhere in my head, if not as the entire system, then as an additional component to a more conventional setup. the theory seems sound, and "they" have got them working, so they may be worth a bit of experimentation.
i used large nylon brushes (albeit non-rotating) as part of a koipond filter i built once, and was impressed with the way they performed, hence the idea of a couple of rotating roadsweeper brushes coupled together and powered by the outflow, or inflow pressure to the rearing tanks.

tsicar

will gladly help if i can, BUT
i am no expert on biofiltration.
everybody will have their own favourite design or system., and what might work for one guy, may not work for another. best you can do is to glean as much information as you can, study the principles and chemistry, and try figure out what will work for you.
mellow uses trickle towers successfully. i prefer multiple chamber systems. neither of us is wrong. his system works for him and my system worked for me.
best is to start off small, as you said you were going to do,
with one tank, then experiment and monitor, learn and extend, push the envelope until you know what you have is working and what the limitations are, then share the information with the rest of us.
in this way we can all learn and pick up tips, and improve.
nobody is just going to copy someone's design, stock up to the max. and become successfull overnight. whatever you do will be a learning curve, some heartbreak, plenty of frustration, and, hopefully, finally, success.
don't give up!

DaffyDuck

Any point in keeping ponds covered by some kind of translucent tarps - mainly to keep birdshit out of the water, to protect against some of the disease factors and carriers?

tsicar

no, the birdshit will do no harm, just adds some fertilizer for algal growth.
disease only seems to become a factor in systems where the fish are stressed by poor water quality and/or overstocking.
almost ALL fish die-offs can be ascribed to poor water quality, or depleted oxygen levels. disease is hardly ever a factor, and when it is, the cause comes back to water quality issues in most cases.

mellow

Here is a place where you can read about ponds:
Pond Construction and Filtration - Koiphen.com

The principles in Aquaculture remain the same. It's up to you how you apply them.

The bird shit is actually beneficial to your pond.

tsicar

exactly.
and you can ignore the known science at your peril.

Smithson

They are very tricky to configure, sometimes they don't kick in, sometimes they don't stop running. The idea for AP is that the flood and drain cycles suck air into the grow beds supplying oxygen to the roots.

Mellow, your planning on using concrete, have you considered a pond liner? There are some good ones made in Thailand, but they are generally exported, so finding the suppliers is difficult.

Smithson

interesting system. where is the media though.
i assume that the media is alternately in contact with air and then with the water[/quote]

The media hasn't been added, this system looks to be in the test stage. You're correct, it is in contact with both air and water. The barrel fills, then the siphon kicks in and it drains.Media used is either gravel (heavy) or expanded clay (expensive).

Here's another pic:

mellow

^ Lava rock is suppose to work well, and its not heavy.
Tanks are a lot easier to work as compared to a pond.

tsicar

The media hasn't been added, this system looks to be in the test stage. You're correct, it is in contact with both air and water. The barrel fills, then the siphon kicks in and it drains.Media used is either gravel (heavy) or expanded clay (expensive).

Here's another pic:
[/quote]

ok, now i see it. only saw the empty tank before. the coarse growing medium is the biomedia, with the added benefit that the plant roots chomp the nasty ammonias and phosphates.

looks good.

Smithson

I'm guessing you mean concrete tanks made from rings? There are some nice plastic tanks around, but not cheap. They have plug holes in the center and would be perfect for the whirlpool effect to remove solids.

BillyBobThai

Tsicar, you mentioned in an earlier post about wanting to use some sort of a road sweeping brush mounted on a powered circular filter. My thought is to have a paddlewheel with the paddles closely spaced and covered with astro turf type carpet. Instead of using water to power the wheel, use a small DC servomotor drawing only a couple of watts.

On another note, the pumps that the locals use to flood their fields are these long pipes with and enclosed prop at one end and their iron buffalo hooked to the other. These pumps do not put out any pressure to speak of, and will not push water to up to a great head, but they put out huge volumes of water. Does anybody make a smaller version of this pump? It shouldn't take a lot of power to run something like this.

tsicar

or the blue 44gallon drums pictured in your "syphon" system. farang price in isaan used to be about 400baht each.
on the same note, i saw those insulated plastic "refrigerators" that they use in thailand. you get one for free if you buy the ice from the same ice factory to keep it working. the big ones are perfect for catfish tanks, if modified a bit. i am sure that a couple could be convinced to "fall off the back of a truck" to supply the cause......

tsicar

ok, you would be creating a type of rbc, and it would work, but nobody knows how well, or whether the astro turf would last, or rot, or fall off, or clog, so experimentation is necessary. your mention of the dc motor, though is a good one.
there are small 12 volt dc pumps available, plus a large rbc could easily be driven off a small geared down dc motor.
if you ran it all off a couple of truck batteries connected in parallel, and charged them permanently from a 12 volt transformer coupled to a bridge rectifier (all really cheap shit and does not need a genius to connect up), you could buy yourself a few hours of drinking time during the frequent power cuts in isaan that would normally have you scampering for the generator to save your fish.
alternately you could use an invertor and a solar panel to charge a few batteries to take care of this problem if using 220 volt ac., or at least supplement some of the power requirement.
once again it is easy to calculate what you will need coz the invertor has a power rating, the batteries have an amp-hour rating and you can calculate and tailor it all to what your requirements are.since all waterpumps have a pumping capacity and head height rating, it is easy to calculate what size pumps you will need. the newer type submersible pumps for koiponds are extremely energy efficient, although probably would not supply the head you would need for a trickle tower.
the thai dirty-water pumps (those long tubes with the kubota thing would draw too much power. as i remember the kubota is around 8-10kw and you would never need as much power as that for pumps to power a few tanks.
calculate how much you need to pump per hour to attain a water exchange rate of once per hour per tank, and buy a pump with a rating of slightly higher than that. remember to figure in the head rating especially if you need to pump up to a tall trickle tower.

Smithson

Price for the 200lt plastic drums is around B450 in Bangkok, could probably get it a bit cheaper if you bought lots.

These are the cheapest way in terms of volume, but the problem is they are still quite small, which means lots of plumbing and fiddling around. Unlike the 120 lt ones, it's difficult to know what they've contained, often it's shampoo etc., but even then the labels still contain warnings.

The concrete rings are much cheaper, everything included they are less than 1B per liter.

mellow

Prefab concrete rings are good and and cheap. 1.20 meter ring ( concrete pipe) by 40 cm high, I paid 350Baht for. Stack 3 of them and you got a 1000 liters of water to work with per tank.