A Community and Forum For Aquaponic Gardeners
liner leaching
Hi
I am considering buying a roll of 800 gauge high density polyethylene to line my growbeds, is 800 gauge heavy enough? i'll be using pea gravel as grow media,a roll of (HDPE) is very expensive, i want to use plastic or rubber pond liner but i was concerned about the plastic leaching into the water!, does rubber leach? would leaching in ap systems gb or ft liner's hinder AP farmers from obtaining an organic cert?. thank you.
Replies to This Discussion
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Permalink Reply by Greener on
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Good idea with the fence panels and liner, probably can't beat the price (though personally I would use LDPE if I went the liner route; I've read LDPE is organic-certifiable whereas EPDM isn't, which makes me wonder a little about EPDM). Unfortunately there are many more points of failure as compared to single-cast tanks, so I think I will stick to those. In fact I may go all Rubbermaid now.
I'm trying to estimate how big of a sump I'll need. Is there a rule of thumb about how much volume gravel takes up in a GB? Or more directly, roughly how much water would drain from a flooded 100 gal GB filled with ~1" gravel? Thanks!
UPDATE: From what I just read online it sounds like I should expect just ~20 gal of water to drain. Sound about right?
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Permalink Reply by TCLynx on
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All rubbermaid is great (that is kinda what my 300 gallon system is. 300 gallon in ground for the fish tank and 100 gallon tanks for the grow beds. I use an Aquaponics Indexing valve for flooding the grow beds in sequence so I don't even need a sump for that system.)
As to how much water is needed to flood a grow bed. I always say to estimate sump tank volume using 50% of the total grow bed volume if you are doing CHIFT PIST and not using an indexing valve. So if you are doing a 2:1 grow bed to fish tank system CHIFT PIST then your sump tank needs to be at least equal to the fish tank. I use the 50% rule since you need to have enough water left over in the sump so that the pump doesn't suck too much air and burn up and most pumps can't suck a tank completely dry. It is also good to have enough extra sump tank volume that you have a few extra inches of depths between the normal low water mark and the pump sucking air to install a float top up valve.
An estimate of how much water it actually takes to flood a grow bed has often been quoted at about 40% but then as a system matures that number will fluctuate as the root mass changes.
Greener said:Good idea with the fence panels and liner, probably can't beat the price (though personally I would use LDPE if I went the liner route; I've read LDPE is organic-certifiable whereas EPDM isn't, which makes me wonder a little about EPDM). Unfortunately there are many more points of failure as compared to single-cast tanks, so I think I will stick to those. In fact I may go all Rubbermaid now.
I'm trying to estimate how big of a sump I'll need. Is there a rule of thumb about how much volume gravel takes up in a GB? Or more directly, roughly how much water would drain from a flooded 100 gal GB filled with ~1" gravel? Thanks!
UPDATE: From what I just read online it sounds like I should expect just ~20 gal of water to drain. Sound about right?
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Thanks TCLynx. I will stick with the conservative 50% value if I go the sump route... I say that because now I'm really interested in your Indexing Valves! Cutting out the sump would be great (as long as the FT water level doesn't change by too much).
From what I understand, for the valve to work you must have a timer turn your pump on and off. Is that correct? But it also sounds like with this method of sequenced flooding you don't need a siphon anymore, GBs can just slowly drain through small holes in their bottoms. Is this true?
How long have you been using the indexing valve, and how has it held up?
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Yes, the simplest way to operate the indexing valves is with a pump on a timer. How much time between beds and how fast you set the beds up to drain will dictate how much the fish tank level fluctuates but you can easily manage a 2:1 system with the indexing valves.
No need for a siphon just have some stand pipes that you put some holes near the bottom (it is nice to install them such that you can pull the stand pipe out to fast drain a bed or eve flip it over to keep the bed flooded if you need to for some reason.)
It is possible to use the valves in ways other than with the pump on a timer but that is definitely the simplest way.
I have been running a specially modified valve under gravity flow on my big AP system for over a year now but that install required me to design and build a special low pressure automated valve to stop and start the flow to the indexing valve. I have heard of people setting up where they use a solenoid valve to start and stop the flow to the indexing valve but that requires a large solenoid valve and a very powerful pump to make the solenoid operate properly.
I have been testing the valves under lower flow and lower pressure applications and I'm working on figuring out the smallest pump that will operate the different valve configurations. I've even managed to get the 1 1/4" 4 way gravity modified valve to work well using a barrel ponics type flush tank.
So, I've had a gravity modified 1 1/2" six way valve running for over a year on my big system, holding up very well.
I've had a 1" six way normal Aquaponics valve running from a float controlled 1/3 rd HP pump feeding my line of bamboo barrels and that has been running well for I guess 5 months.
More recently I've hooked up a 1 1/4" gravity modified 6 way valve with the 3 port cam and I found that my Quiet One 4000 pump didn't operate it as reliably as I would like so I upped that to the Quiet One 5000 pump. But now that I've been running pump and valve tests I've been swapping pumps and valves on that set up to test each configuration out.
Rupert of OZ has been running the indexing valves for over a year now too. In the Americas I can put you in touch with a distributor for your area when you are ready to buy. For the rest of the world, Contact Rupert.
This link can get you in contact or link you to the people who can sell these.
Aquaponics Indexing valves
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Permalink Reply by Michelle Silva on
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I read on the Friendly Aquaponiocs FAQ that they have used 20mil Dura Skrimm. I had bought this same liner and now trying to return it because the billboard liners are the same thing.
Chris Smith said:We use low density polyethylene that is 20 mils. This is a food grade liner that can be certified organic. HDPE is much more expensive. Rubber liners like EDPM will leach into the water. If it smells like a tire you don't want to grow food in it!!
If you are planning to make a commercial system I would discourage you from using media. There are so many advantages to using the raft system for a commercial setup The biggest if that everything on the farm is mobile. Without planting roots in media, everything can move around. When plants are small I keep them in a tight spacing then spread them out to a final grow out spacing after a few weeks. This saves me valuable grow out space increasing my overall yield! I put small plants into troughs at one and harvest from the opposite end which makes harvesting much more efficient. Check out some of my pics to see this.
Aloha
Chris
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Oh yeah, and I think billboard liner is LDPE as well.
Michelle Silva said:I read on the Friendly Aquaponiocs FAQ that they have used 20mil Dura Skrimm. I had bought this same liner and now trying to return it because the billboard liners are the same thing.
Chris Smith said:We use low density polyethylene that is 20 mils. This is a food grade liner that can be certified organic. HDPE is much more expensive. Rubber liners like EDPM will leach into the water. If it smells like a tire you don't want to grow food in it!!
If you are planning to make a commercial system I would discourage you from using media. There are so many advantages to using the raft system for a commercial setup The biggest if that everything on the farm is mobile. Without planting roots in media, everything can move around. When plants are small I keep them in a tight spacing then spread them out to a final grow out spacing after a few weeks. This saves me valuable grow out space increasing my overall yield! I put small plants into troughs at one and harvest from the opposite end which makes harvesting much more efficient. Check out some of my pics to see this.
Aloha
Chris
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Great stuff TCLynx, thanks so much.
I would like to get rid of the timer if possible, thinking of different ideas.. I'd also like to have a continuously running pump as I assume this will provide a longer pump life.
How are your indexing valves 'gravity modified'?
From what I'm reading these valves are reliable and are widely used in other industries. I like this idea more and more. Seems a lot better than having a sump! As long as you have a float switch to prevent the FT pumping out in case of a leak somewhere, this idea seems to be the best IMO.
Do you know what materials are in the Aquaponics Indexing Valve you sell? Is there any oil involved?
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A flush tank set up might be an option if you want to run the pump constantly and avoid a sump tank but a flush tank and the flush valve are going to need regular checking since there are additional parts to fail.
The indexing valves that are gravity modified have a shortened spring. I've been working with the manufacturer, testing these to work out how much the springs can be modified before the valves stop functioning properly. Any of the distributors should be able to ask for the gravity stems for the valves if that is indeed what you need.
The valves are mostly plastic (I would have to call the manufacturer to get the exact types of plastic for each part.) There is of course some screws holding the parts together and the spring as well as some O rings and a rubbery material disk that seals off the unused outlets when the valve engages. The manufacturer here in Florida molds all their own parts except for the screws, springs and O rings.
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Permalink Reply by David Hart on
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The up rights are posts from tractor supply. The side boards are PT fence boards from Home depot. I added 3/4 inch sytrofoam before I added the liner. This is 3'x3'x9'
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Permalink Reply by kevin darcy on
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Nice job david
Greener said:nice looking tank David!
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Permalink Reply by RupertofOZ on
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Greener said:
The original prototype valves were made of ABS plastic... the "aquaponics valve" now available is produced from ASA plastic as opposed to the old ABS.Do you know what materials are in the Aquaponics Indexing Valve you sell? Is there any oil involved?
TCL said:>How much time between beds and how fast you set the beds up to drain will dictate how much the fish tank level fluctuates but you can easily manage a 2:1 system with the indexing valves.
In fact you can go far beyond a 2:1 system... easily to 16:1.... simply by daisy-chaining the valves
There is no "oil" in any of the "aquaponics valve" parts... and I've actually been running these valves on my systems now for near two years or more... since the first prototype testing...
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