neighbor

small iAVs in California

52 posts in this topic

I'm starting this thread as a place to collect info on the work related to this project, currently (half-)planned to utilize 2 IBC totes

- one will be split 1/3 - 2/3 - with the 2/3 portion to be used for fish (koi or goldfish - or other fish that can tolerate our extreme daily temperature fluctuations - as much as 50 degrees F  low/high difference in any given 24 hour period)

- and the other 1/3 portion for a growbed.

- The second IBC will be split into top and bottom 1/3s (1/3 appears to be deep enough for a 13' depth of sand, but I'll modify it if needed) or top and bottom halves if it seems pointless to waste the middle 1/3 of the IBC

 

Based on my understanding of the ratio of water to sandbed size, I think I can safely link two 1/3 sections to the one fish tank. This leaves me with a "loose" 1/3 section. I may experiment (later) to see if I can put that extra one into the loop.

 

Let me state up front: I am slow. This is a work in progress and, fundamentally, a practice run. I have no aquaponics experience, have never had fish larger than goldfish, don't have any experience with construction or setting up plumbing or PV panels. I have some garden experience. If I can make this work, pretty much anyone can.

Edited by neighbor (see edit history)
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What's influenced my system so far?

 

I live in a drought-prone region, with seasonal rains. Our typical annual drought of 6 months is compounded by long-term changes that decrease the amount of rainfall we do receive and increase the likelihood of extreme heat (and therefore, transpiration).

 

I work alone, for the most part - so I have to be able to do everything on my own, though I do have a relative about 1.5 hours away who sometimes helps - he has some of the tools I need, too, like the dremel to cut through the IBC cages.

 

Money is a limiting factor. I've chosen to utilize IBCs because I can get used food grade ones for a decent price. I also like being able to take something out of the 'waste' stream rather than using all new materials. Also, I'm curious to see if this can be a model of a small iAVs system that people without a lot of room can do - so with a readily available material like IBCs, maybe this can be a feasible small-yard system.

 

I'm aiming for system resilience.

- I'll be linking my pump/timer to a 12v solar system - with a copy of Do it Yourself 12v Solar Power in hand because that's all new to me. I do currently have access, though, to electricity through the local utility.

- Water will initially be supplied by local utility (currently providing groundwater - high in dissolved minerals, lots of boron, etc, but our city will be switching to river water in the near future or will mix the two sources) - I just installed the first of my rainwater harvesting tanks, however (2 IBCs x 275 gallons for a total of approx 600 gallons), so hope to use rainwater eventually.

- fish - as mentioned above, have to tolerate weather like we're having now (lows in the 50s, highs going up to the 90s . We have frost in the winter (no snow, no hard freeze). I currently have to work within the confines of some family members' values - I can't raise fish for consumption. 

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Today I started some of the 5 gallon bucket test for sand quality.

 

Sample 1 is "playground sand" and what I was given when I requested "pure silica sand." 

Cost: $63/cubic yard

 

Sand, sample 1

sample 1

sample 1, vinegar test

sample 1, shaken

sample 1, shaken, 10 minutes

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Hey Neighbor....pretty exciting stuff!

Don't forget your vinegar test before you have a truckload of sand delivered.

 

Keep us posted.......mh

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Thanks Mike, for pointing out that my descriptions don't show up, only the titles do, if you hover over the pics with your cursor.

 

Pic #3 is the vinegar test - no bubbles (other than one or two air bubbles making their way up from the bottom).

 

Pics #4 & 5 are immediately after and 10 minutes after the turbidity test. :|   I just got home and 2 hours post-shake test the water's clear(ish)!

 

It has a clearly discernible layer of what I'm guessing is silt.

 

Oh, and if anyone missed it, the 5 gallon bucket test is here.

 

Here's my sample 1:

sample 1, 3 hours post shake test

 
I still need to get a "5 gallon bucket" equivalent (the soda container, since I don't have 5 gallons worth of sand) to do the percolation test.
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Hi Wendy,

 

Congratulations on your start up.

 

Feel free to ask questions as they come to mind.

 

Gary

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Finally.. good to see you broke that lethargy in taking the first step to iAVs.  I am sure there are several other forum lurkers inspired by seeing how you grow with this.  All the best of luck to you, neighbor!

 

To match the suggested volumetric ratios of iAVs, I guess you would need two to three slices of IBCs.

 

Did you check the source water pH and that of chosen sand's effect on it?

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vkn,

 

nope, not yet. That will happen in conjunction with the perc test.

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pH test shows (as expected) relatively high pH. We're on groundwater which is known to be high in dissolved minerals (hard) - so much so that while I cook with it (soups, etc), we don't drink it straight - it'll ruin a kettle in no time flat and tastes terrible.

 

There are pics in the gallery of the first test that prompted me to undertake a "high pH" test. The colors on the card leave a little to be desired, but I'm guessing we're around a pH of 7.8.

 

For grins & giggles, I may just test the filtered (tap) water to compare. In the meantime, I'll be doing a modified bucket test (with a 2l soda container since I don't have enough sand for a 5 gallon bucket).

 

Question: In the next month our city will be switching to treated surface (river) water or a mix of surface & ground. If it's unclear when we'll be getting a mix (and at what percentage) vs. straight of either ground or surface water, how can I plan for high variability?

 

***

eta - I just noticed that Mike is working with a pH of 8.5 … I guess 7.8 isn't 'relatively high' is it?

Edited by neighbor (see edit history)
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Hi Wendy,

 

Since sand is central to the efficacy of iAVs.....and, as such, it has probably overshadowed the other essential element of any integrated aquaculture system.....water!

 

Mark and I have been talking about how to sheet home the pH message effectively.  Don't take what I say personally because this message is directed at all aspirng iAVs builders and operators. 

 

The water used in an iAVs must be pH 6.4 (plus or minus 0.4).

 

If the source water is higher than that, then it should not be used until the pH has been adjusted to that level.  In practice, that means filling a container (200 litres or more) with water and adding an acid solution (we suggest sulfuric acid) so that it settles at the prescribed level.  Use that water to fill - and make up for evapotranspiration - as required.

 

In the medium term, the simple solution is to use rainwater - which is usually pH 7.0 or below.....and better for all of the things that it doesn't contain.

 

Until you get the rainwater sorted, adjust your source water.  Believe me, you will notice the difference in how your iAVs performs.

 

Gary

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Why is that Gary?  Do you have to buffer system ph up in IAVS as with 'conventional' AP?

 

or do you mean the system water must be this ph, rather than the source water?

Edited by mattyoga (see edit history)

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I don't think I could take it personally unless you were trying to accuse me of tampering with the groundwater, personally :)

 

I'll be interested to see if the pH drops noticeably after our water system switches sources.

 

And I did follow the sulfuric acid sub-topic (on vkn's experimental thread, I think?) - thanks for mentioning it here, in relation to my case, too. I've been so focused on sand that I hadn't gotten around to figuring out water yet. 

 

I think it's actually a good thing that I'm slow - I mean I'm certain I'll screw something up somewhere, but maybe I can avoid some of the "easily avoided" problems just by virtue of my plodding pace.

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I've been so focused on sand that I hadn't gotten around to figuring out water yet.

[vkn] Every early adapter of iAVs that we have seen so far went through your situation. That is why I asked you about water pH in my first comment. You understood it pretty quickly though.

Patience, a lots of it you would need while working with high pH water. Did you check your carbonate hardness?

In most cases, acidification from good nitrification (at peak efficiency) leads to a naturally low pH and you would not want to add anything. I also remember having a discussion with Ravnis on this subject.

I have also read somewhere that even Reverse Osmosis (RO filter) of your source water can remove high carbonates.

Edited by vkn (see edit history)

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Why is that Gary?  Do you have to buffer system ph up in IAVS as with 'conventional' AP?

 

or do you mean the system water must be this ph, rather than the source water?

 

Hi Matt,

 

iAVs is conspicuous among integrated aquaculture systems in that you don't need to add supplements like calcium, iron and potassium (or anything else for most plants).....if you operate the system within the prescribed pH range.   Once you get much above that range, nutrient availability becomes an issue.   Back in 2009, I featured an article on nutrient availability on my Microponics website....HERE.

 

We've discussed pH at length in the various iAVs threads....but the focus has been on sand containing carbonate and its impact on the pH of water with which it has contact.

 

If your sand contains carbonate (high pH).....and your source water is also high pH.....you have a double jeopardy - and your plants will suffer.

 

If you stabilise your make-up water at the prescribed pH....and then add it directly into the sand bed....you will mitigate against any carbonate issue that exists in the sand (as far as is possible).  Ultimately, how big an issue carbonate in the sand is will depend on how much of it there is.  A small amount will (in the presence of consistent pH adjustment to the make up water) eventually be neutralised.

 

The pH in an iAVs (assuming sand of the correct spec) will stabilise at around 6.0 to 6.4.....so long as you have growing plants in the sand beds.  If you remove all of the plants, the pH will drop like a stone.

 

Wendy....

 

I don't think I could take it personally unless you were trying to accuse me of tampering with the groundwater, personally :)

 

Some people cope with advice better than others.  Those who take advice around iAVs will get the best results.

 

I'll be interested to see if the pH drops noticeably after our water system switches sources.

 

If it's not in the specified range, then fill a container (blue barrel or IBC) and dose it with sulfuric acid.  That's directly from the mouth of the master.

 

There's nothing to fear in using acid.  The only residues arising from its use are trace amounts of sulfur - an element used by plants.

 

The consequences of not using it the in the presence of high pH are much greater.

 

I think it's actually a good thing that I'm slow - I mean I'm certain I'll screw something up somewhere, but maybe I can avoid some of the "easily avoided" problems just by virtue of my plodding pace.

 

Once you get the fundamentals (sand and water) in place, iAVs is disarmingly simple....and that's its beauty.  It will work best for those who follow the game plan.

 

 

Gary

Edited by Gary Donaldson (see edit history)

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Great advice and I appreciate that it's now in a location that is easy for me to find (you know how it is, right? you go looking for info you're sure was in a particular thread and have to dig through about six others, each with 10 or 20 pages, before giving up?) - so that these tips are HERE and will remind me to go dig around - armed with 'sulfuric acid' as a search term - will serve as a good bookmark.

 

 

 

Once you get the fundamentals (sand and water) in place, iAVs is disarmingly simple....and that's its beauty.  It will work best for those who follow the game plan.

 

 

Gary

 

And, not to be belligerent, but I beg to quibble here. I don't see that sussing out the qualities of pumps and batteries is going to be disarmingly simple… :) I think I've been putting it off. I did, however, get a timer. Small victories :D

 

Later I'll post a picture of the part of the yard I'm going to put this in and see if I can solicit layout ideas. I've probably picked the most difficult part of the yard to work in… and maybe I need to have that notion shot down.

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I have decided… to do nothing!  

 

At least until my city completes its transition to river water - then I'll see where that puts me. It would be premature for me to do otherwise since I won't be ready for water until at least another couple months and any decision relative to today's water will be outdated by then (see first post, where I mentioned I'm S-L-O-W :D).

 

What I'm interested in, though, in terms of my current testing of water - is to see if my sand changes the pH. So far it doesn't seem to, but I'll try again with water that 'flushes' through the sand a few times.

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I'll try again with water that 'flushes' through the sand a few times.

A few flushes won't get you an accurate result. I found keeping it running or fully saturated for more than 36 hours gives a stable result. Edited by vkn (see edit history)
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Well, that's cool, then - because I've had that jar of sand submerged in water sitting on my kitchen counter for… almost two weeks now!!  :startle:  That's what I did the third test with - and found it to be the same pH as tap water that hadn't been in contact with the sand.

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Hey Wendy,

 

I'll trade you sand-for-sand ! 

Sounds like you are in good pH shape then!

 

..........mh

 

Update regarding stubborn high pH, 5-11-16

I have been adding about 25 gals of < 5.0 pH makeup, every other day to my iAVs sand beds. My local city source water has a pH of 8.5, which I have used 1000 mg of crushed vita-C to neutralize the chloramine. After dechlor I add 25 ml of 66% sulfuric acid to a 55 gal barrel which lowers the pH down to 5.0.

My total water volume in the entire system is about 225 gal (not counting the retained water in the two beds). My fish tank is one 275 gal IBC. The pH of the system water before doctoring with 5.0 has been steady at 7.3. I think I have made a tiny bit of improvement, maybe down to 7.1-7.2. It is hard to determine this small of change with the API test kit. My hope is that the carbonate buffer will be consumed by the low pH water additions.

Tomatoes are putting on lots of blooms, but I may get 1 tomato to set for every 20 blooms, not very good. I am sure most of the minerals the plants need are pH locked.

I have been adding the 5.0 pH makeup for about 3 weeks.

I hope my pH holding pattern, will spurn the rest of my fellow iAVs to "trust, but verify" before you buy your iAVs sand......don't make the mistake that the sandman either knows what is in his sand.....or worse, doesn't understand the question.

Just "trippin" here in Oklahoma......mh

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It sounds like you've got extraordinarily hard water there - time to start bottling and selling it as "artesian"? :) I didn't notice that sand was compounding the problem, but if you've not been able to find sand that doesn't contain some kind of carbonate, boy, I'm really sorry!

 

It sounds, though, like you're taking good steps toward reducing the pH and getting things lined up. Keep up the good work!

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Since I was given less than a five gallon bucket's worth of sand, I'm modifying the 5-gallon bucket test.  I'm at the point where I'm testing porosity, hydraulic conductivity and water retention.

 

The pore space volume test shouldn't be a problem - I'll be looking to see if I end up adding 25-30% of the sand's volume in water (that will fill the pore spaces between grains).

 

QUESTION: For hydraulic conductivity, though, how should I figure the amount/size of drainage holes at the bottom of my 2 liter soda bottle? The more the better so that I don't get water pooling at the bottom of the sand (held back by the lack of exits)? What is an ideal drainage time? It's suggested that the test be undertaken 5-6 times but it's unclear how to judge the results (as in, favorable or unfavorable sand).

 

QUESTION: Is water retention calculated by the volume of water added to the sand minus what is collected below the sand (so that whatever doesn't make it into the collection basin is, by default, retained in the sand)? It is suggested, "After the first flood and drain cycle, the exact amount of water retained in the sand will vary according to the elapsed time from the last flood cycle" therefore I would like to ask which results are to be relied on - the first pass of the water through the sand (when it starts out dry) or the later one (when it's wet from the previous flood)?

 

Thank you!

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Hi Wendy,

 

The 2 litre drink bottle will suffice for the hydraulic conductivity test. 

 

QUESTION: For hydraulic conductivity, though, how should I figure the amount/size of drainage holes at the bottom of my 2 liter soda bottle? The more the better so that I don't get water pooling at the bottom of the sand (held back by the lack of exits)? What is an ideal drainage time? It's suggested that the test be undertaken 5-6 times but it's unclear how to judge the results (as in, favorable or unfavorable sand).

 

Drill ten 1/8" holes around the circumference of the bottle......where the side meets the bottom.  That should be adequate for the bottle test.  Fill the bottle with sand to about the 3/4 mark.

 

Drainage needs to be such that the water enters and leaves the bottle in seconds rather than minutes.

 

If the water is draining from the bottom holes while you're still pouring it in (or within a few seconds of having poured it in) it's good.  If you've poured the water in and you're looking at it (tapping your foot) and waiting for it to begin draining from the bottom, it's probably not so good.

 

I'm loathe to get more prescriptive than that for fear that people will attach to an indicative number and get hung up on that.

Edited by Gary Donaldson (see edit history)

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QUESTION: Is water retention calculated by the volume of water added to the sand minus what is collected below the sand (so that whatever doesn't make it into the collection basin is, by default, retained in the sand)? It is suggested, "After the first flood and drain cycle, the exact amount of water retained in the sand will vary according to the elapsed time from the last flood cycle" therefore I would like to ask which results are to be relied on - the first pass of the water through the sand (when it starts out dry) or the later one (when it's wet from the previous flood)?

 

Once again, don't get hung up on the specifics.  The water retention measurement features in the test article simply to suggest that a quantity of water remains bound up in the sand.....principally after the initial flooding......and that afterwards this quantity of water varies according to how long has elapsed since the last flooding.   We wanted our readers to understand this....largely for design purposes.

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okay, then I think I'm good. I'll let you know what happens :)

 

Thanks for clarifying that there weren't tight parameters I was was somehow missing.

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