Aquaponics build

[Catfishnut]

MirxhM Ghast is a brand name. We are talking about 2 types of compressor from that company: rotary vane and regenerative blowers.

The one I have is a regenerative pump. I did not recognize the type of your pump and assumed wrongly that it is the same. My bad. Your pump sounds like the sort used on automotive smog pumps and I think cabin pressurization for small aircraft.

I used to use used auto smog pumps prior to obtaining the regenerative blower. They lasted a year or two of continuous operation. Ones purchased from auto parts stores did not generate enough pressure. I assume the ghast rotary vane is both more durable and rebuildable. Between the used smog pumps and found motors failing I went to quick and dirty mountings. The unit pictured below was suspended by a tarp strap for sound deadening. There was also a bit of chain to support the unit should the tarp strap fail.

I really want to make a gas powered backup pump. Thinking a lawnmower engine with a rotary vane pump. Do you mind if I PM you as we are stomping on this thread.

Howard,

Certainly, PM me anytime!

Gordy

 

[MitchM]

You're right, thanks. I was thinking of using an extra electronic sensor I have, but I can rig up a mechanical one.
I wouldn't trust the electronic one with the turbulence.

The water level will obviously change as the siphons cycle but there will be some max low point the a float can be set to. The float will go on and off as the siphons cycle until that max low point is restored but that's OK.

 

[crsublette]

What I haven't figured out yet is how I'm going to control the water level from evaporation.

Do a low rate flow through system and have the exiting water enter a soil or wicking grow bed and possibly have an indexing valve that switches between multiple grow beds to prevent the beds from staying too wet. To address the evaporation, this is what I am going to do in my system...

For the drain, add a stand pipe in your lowest tank and just sit it to the level where you do not want the lowest tank to over flow.

For the new water, just very slowly trickle it in your fish tank. Ya can figure the calculations very easy by timing the drip into a gallon bucket of water and then do the math from there.

 

[MitchM]

Except evaporation rates fluctuate, so you would be constantly adjusting the drip rate of the makeup water, wouldn't you?

 

[crsublette]

Except evaporation rates fluctuate, so you would be constantly adjusting the drip rate of the makeup water, wouldn't you?

Plant's consuming the water will also reduce your water volume; as the plant grows bigger to fruit production, then the plant will use tremendously more water. Sweet corn, on a dry, windy, hot day, the plant it self can consume many gallons of water in just one day. However, it appears your system is in a greenhouse so your plant consumption or evaporation rate might actually not be that high. You may actually have to replenish the water due to plant consumption more so than evaporation rate.

In the beggining, while you're trying to figure your actual evaporation and plant consumption rate, you might be constantly adjusting the drip rate every morning or every other day.

After thinking about this more, I might have an "overflow" tank, where the flow through waste water enters, then a sump pump turns on when the water level gets to a particular level and the pump waters the connected grow bed.

To determine if you are replenishing your water properly due to evaporation or plant consumption, then I suppose you could look at how often the "overflow" tank fills up to a particular level. If it takes longer and longer to fill it up, then this likely means you need to bump up the drip rate a little. If you want to try to get really precise, then just use low rated drip emitters, and, if need more water, then just add another drip emitter.

 

[MitchM]

Plus I'll be using evaporative cooling to help control the aquarium temperature.

 

[MitchM]

... Sweet corn, on a dry, windy, hot day, the plant it self can consume many gallons of water in just one day....

Wow, I didn't know that. That must be pretty hard on the surrounding water tables for large crops.

That's what I like about an aquaponics system. It's said to only take about 10% of an equivalent dirt garden's water needs.
We're on well water here and the outside gardens take more water than we have well capacity. Even with rotating the sprinkling pattern I can't get enough water to properly water things.

I wonder if an aquaponics setup needs to have a water change at any time? I doubt that it can remain a closed system forever.

 

[crsublette]

Yeah, one thing you learn quick in farming, when trying to produce hi-yielding corn (260+ bushels per acre) with huge ears, then corn is a sponge. I was told once exactly how much water it absorbs in a single day, but, if I don't write it down, I tend to forget. I do remember it was many many gallons of water out of the soil, but we are also competing with significantly more volatile environmental conditions here in the semi-arid high plains. The water consumption might not be as high in a greenhouse, but I would assume it will still be quite noticeable.

Yeah, for every 246 acres (half section) of irrigatable farmland, we're pumping about 600 gallons per minute, out of the water aquifer. There's a water conservation board that monitors our usage, which I support as long as they don't act stupid such as penalizing folk a few grand for filing their water reports late.

That's what I like about an aquaponics system. It's said to only take about 10% of an equivalent dirt garden's water needs.
We're on well water here and the outside gardens take more water than we have well capacity. Even with rotating the sprinkling pattern I can't get enough water to properly water things.

Oh, I completely believe that the aquaponic system allows you plants to use the water more efficiently. These systems don't have anywhere near the volume of water loss due to leaching or evaporation compared to conventional irrigation.

Underground drip irrigation is available in my area. It essentially irrigates the fields like a wicking grow bed and it cuts evaporation loss down to almost zero. However, there is still water leaching concerns, increased maintenance, and these agricultural underground irrigation systems cost $1,300 per acre, which is insane. Land with all the above ground irrigation system improvments and utilities is only worth approximately $1,800~2,500 per acre (most on the lower end due to water scarcity). For folk who are unaware, to put this into perspective, the very excellent land in the midwest cost around $8,000~13,000 per acre. Tremendously expensive for a farm to purchase new land. Anymore nowadays, many folk lease or form big partnerships (which is quite risky) to buy land.

I wonder if an aquaponics setup needs to have a water change at any time? I doubt that it can remain a closed system forever.

I think, if an AP systems is properly setup along with a proper UV device, then there should be zero need to do water changes. However, personally, I would do a low flow through rate to act as my small water change to help replenish the minerals in the water and use the flow through waste water to irrigate some other differently designed grow beds.

 

[MitchM]

...

I think, if an AP systems is properly setup along with a proper UV device, then there should be zero need to do water changes. However, personally, I would do a low flow through rate to act as my small water change to help replenish the minerals in the water and use the flow through waste water to irrigate some other differently designed grow beds.

Right, but different plants require different nutrients. Some prefer alkaline soil and others acidic.
Tomatoes for example require calcium. If my makeup up water is RO/DI, then I'll need to supplement calcium.
If I don't have tomatoes and instead use my well water for makeup which has about 290 ppm calcium (if I remember correctly), then I'll eventually wind up with overly hard water in the system.
(this is starting to sound too much like an aquarium, lol)

 

[crsublette]

Yep, tomatoes and many other blooming plants require calcium for new growth. In particular to tomatoes, calcium deficiency is one of many causes that leads to blossom end rot.

All of that calcium might not be available to you. Calcium availability is dependent on the pH. When pH goes above 7.2, then calcium acts like a free radical that binds other nutrients into plant insoluble nutrients. An easy way to counteract this is by using more fertilizer, but, if there is a reasonable option to reduce the pH to around 6.5~7.0 by using rain water or di-RO water, then I would do it. Calcium most specifically enjoys binding with potassium. I have read about fields that tends to be calcium deficient when using fertilizers very high in potassium. Potassium also allows the nitrogen to be consumed more efficiently by the plant and helps the plant to be more drought tolerant. Many other nutrients act the same as well with how they have a mutually exclusive relationship with other nutrients.

Although there are plants that can tolerate alkaline soil, this does not necessarily mean they prefer more alkaline soil. Tolerance and preference should not be viewed as the same.

So, there is this give and take with it all, pH makes a big difference, and this is why there are folk always trying to find that "perfect" fertilizer blend.

 

[crsublette]

Yep, I tell ya what.... Managing aquaponic systems can become just as complex as managing anything else involving water. Some folk get really heavy into the details and other folk simply just go out to buy a retail fertlizer that they use through a periodic foliar spray system on their grow beds, especially during germination.

 

[MitchM]

At the end of the day, my plants will tell me if anything is wrong.
I think the fish will be easier to keep healthy.

 

[Waterbug]

Yes water changes are needed. How often depends on your water supply. In my area salt is the biggest issue and is in the range of 200 - 5,000 mg/L for source water. So at the end of a single season water in the system can be in the 2000 - 50,000 mg/L range if no water changes were done. Saltwater is 35,000 mg/L. So without water changes things can go south pretty fast.

Fish also have built in health indicators...they show you their bellies.

 

[crsublette]

Wow. That really proves my point of how the source water must be considered when doing water changes and how it can impact a system. A shift of .02~.5% to .2~5% salinity concentration change is a huge change from not doing water changes at the end of a season. Makes sense to use a different source water or to dilute the source water with something else if possible to avoid costly big water changes in attempts to combat that salinity.

Really makes me wonder how well the yield is of paritcularly low salt tolerant crops when using that water in a water based garden system, such as aquaponics, unless a soil mixed wicking grow bed was used to help combat that salinity.

 

[Waterbug]

Makes sense to use a different source water or to dilute the source water with something else if possible to avoid costly big water changes in attempts to combat that salinity.

Different source water??? You mean like bottled water? Truck it in from Colorado? Collect rain water? Kind of expensive vegetables.