MT Mind

Small iAVs in West Texas

19 posts in this topic

Welcome to our SandSourcingAdventure....

 

I am considering the crushed granite experiment here in OKC too, as it seems that all sand that I have found is loaded with "carbs".

 

Keep us posted MT and best of luck!

Share this post


Link to post
Share on other sites

Nice color!  I read somewhere that mountains of San Diego are full of such red soil that are full of Iron oxide.  The Iron comes from the dark minerals of the rocks.

 

I am equally enthusiastic about your project and the stories it tells.  Welcome to the gang!

Share this post


Link to post
Share on other sites

Hi MT Mind,

 

Welcome to the fraternal order of iAVs.

 

After searching for months to find suitable sand for a small iAVs system, and repeatedly failing to do so, I have settled on a less-than-ideal scheme to sieve the sand from a batch of decomposed granite.  I was able to get a sample of the decomposed granite from a local vendor - recomtx.com - and have been experimenting with it a little.  The raw material is granite gravel, sand, silt, and a little clay, with the largest gravel being 1/2" or 13mm.  

 

The effort to get sand of the right specification will yield dividends in the end.  You will get to realise the full potential of iAVs and to experience it as it was designed.  

 

The clay (and hopefully most of the mica) will wash out of the sand pretty readily......and the gravel can be put to good use on your driveway or garden pathways.

 

There were no indications of bubbles during the vinegar test, but I did notice that the silt and clay settled differently in vinegar than in pure water.  In water, the material settled out as you might expect, with progressively smaller particles settling to the bottom, and the cloudy clay suspended for days in the water.  With the vinegar, the cloud seemed to stabilize early on, like a coagulant was present, with a defined boundary developing between the suspension and the clear water above.  This boundary descended slowly, with the suspension becoming more concentrated, and a few little holes appeared in the surface of the clay, apparently where water from below was escaping the pressure of the falling clay suspension.   I'll try to reproduce this and get some time-lapse to show what I mean.  I tested the water pH before and after mixing in the material, and there was no change, so I'm not too worried about the vinegar thing.

 

I find all of this interesting....and it may offer some insights into ways to separate sand from clay, silt and other materials.  It's certainly worthy of more experimentation.  It's clear that there's lots of things that we don't understand about this seeming fundamental material called sand.

 

Good luck with the separation process.   I don't think you're going to be the last person to undertake the laborious process of separating sand from gravel so your experience will be of interest to many.

 

Gary

Edited by Gary Donaldson (see edit history)
neighbor likes this

Share this post


Link to post
Share on other sites

Oh boy, the sand saga is something!

 

I'm sure you'll zoom right on past me and have this thing set up in no time. Go!!

Share this post


Link to post
Share on other sites

I was able to find sands that would likely have been perfectly suitable, but between minimum orders and shipping costs, none of them were really viable options for a small system.  I could have taken the plunge and bought several yards of something in bulk bags, had them delivered from 300+ miles away, and spent the summer building a substantial system under a greenhouse in our back yard, but we're hoping to move to central Texas by the end of the year.  Everything would just be coming together by the time we had to abandon it, and I'd be starting over from scratch at the new location.

 

Ironically, I would have already been running an aquaponic system by now if I hadn't stumbled across the iAVs website. I had just bought some 17 gallon (64 liter) tubs for media beds, when I started looking online for the best way to grow root vegetables.  A google search for "aquaponic sand bed" led me to Aquaponics' Biggest Mistake, and the more I read, the more I realized that my concerns about aquaponics were not an issue in the original system.  I figured I should do more research before putting anything together, and eventually decided to build an iAVs for my first little system.  Several "Aquaponics Experts" online had specifically stated not to use sand in the system because it would hold water and become anaerobic, but I guess they hadn't tried the right sand.

mhaigh and neighbor like this

Share this post


Link to post
Share on other sites

I was able to find sands that would likely have been perfectly suitable, but between minimum orders and shipping costs, none of them were really viable options for a small system.  I could have taken the plunge and bought several yards of something in bulk bags, had them delivered from 300+ miles away, and spent the summer building a substantial system under a greenhouse in our back yard, but we're hoping to move to central Texas by the end of the year.  Everything would just be coming together by the time we had to abandon it, and I'd be starting over from scratch at the new location.

 

I understand.  Moving an iAVs is impractical unless it's something like our new small iAVs demo system (and even that took time).

 

Between now, and when you move, have fun with learning what you can about sand.  Get a sense of what works.....and what doesn't.  Given that you are going to be limited by time and availability of the correct sand, feel free to experiment a bit.

 

Neither Mark, nor I, have said that iAVs won't work outside of the specified sand parameters.  We've largely reported what Mark did and what results he got.  Our recommendations around all aspects of iAVs are based on that experience (coupled with Mark's knowledge of horticulture and the associated chemistry). 

 

VKN's efforts evidence that you can grow things.....even when the sand and water are less than they should be.  The unanswered question is about how much better things would grow if the conditions were optimum.  The answer to that question is research......and shared information.

 

Ironically, I would have already been running an aquaponic system by now if I hadn't stumbled across the iAVs website. I had just bought some 17 gallon (64 liter) tubs for media beds, when I started looking online for the best way to grow root vegetables.  A google search for "aquaponic sand bed" led me to Aquaponics' Biggest Mistake, and the more I read, the more I realized that my concerns about aquaponics were not an issue in the original system.  I figured I should do more research before putting anything together, and eventually decided to build an iAVs for my first little system.  Several "Aquaponics Experts" online had specifically stated not to use sand in the system because it would hold water and become anaerobic, but I guess they hadn't tried the right sand.

 

Imagine what the world of aquaponics would look like now had it not been for the wilful ignorance of the Speraneos....and some similarly unfortunate strokes of fate.  

 

As for the "experts"....they are not!  

 

What they do have in common is (as Ravnis pointed out recently) is absolutely no experience of growing in sand.  Most of their pontifications are born of what might happen.....and an incomplete understanding of how iAVs works.....or a  fundamentalist attachment to another model.  

 

There is only one expert in iAVs and that's Dr Mark R McMurtry......and, with his ongoing help, we (and that includes you) will see iAVs assume its rightful place in integrated aquaculture.  It was the original....and it's still the best!

 

You are a pioneer in the fledgling iAVs movement......and you have every reason to be proud of your efforts - now and in the future.  And that goes for everyone else who is working to make sand a better place to grow food.

 

Gary

Edited by Gary Donaldson (see edit history)
neighbor likes this

Share this post


Link to post
Share on other sites

One thing to consider, is when you move to central Texas, you might be able to find a different sand source to get a better sand locally there. Might be able to use th is time to check out suppliers in that area if you have not already done so

Share this post


Link to post
Share on other sites

Finally finished sieving my yard of 1/2" decomposed granite.  I didn't even realize it had been so long since I started; we've been out of town quite a bit this month.

 

The process started with a screen of 1/8" hardware cloth, with anything larger being used elsewhere.  I would load about 4 gallons of the sand/silt/clay into a 5 gallon bucket, and shove the garden hose down into it.  As the water rose up through the sand, i would stir it by hand or with the action of the water until the water leaving the bucket was more or less clean of the cloudy clay.  After that, i used a cheap kitchen strainer in the top of a bucket of water to wash out the fine sand and silt from the larger grains.  I collected the larger grains in a separate bucket and washed them again when there was about 3 gallons.  After that, the finished sand went into the grow bed.  The smaller sand/silt was also washed, and that'll be going into a small sandbox for my daughter; I have about twenty gallons of it.

 

The grow beds are two 17 gallon rugged storage totes that happen to have channels in the base.  I drilled a 3/16" hole in the end of each channel for drainage, so there are 28 holes around the perimeter of each tote.  Some initial flooding of the beds with the garden hose showed adequate drainage without loss of sand.  The totes are on a collection tray that will direct water to a return line to the fish tank.  At the moment, the fish tank is a 20 gallon clear plastic tote, but I may find something more suitable this weekend.

 

I filled a glass measuring cup with 4 Cups of dry sand, and the water added to match was about 1-1/3 Cups.  That comes out to 41.5% pore space, which is alright with me.  I performed the bucket drainage test repeatedly on a bucket that had about 4 gallons put in it two days ago, so the top of the sand had dried out a bit, as would be the case in the morning with an operating system.  Water started to exit the bucket within seconds after the water was poured in; after the second or third flush, water started exiting the bucket about the time I finished pouring.  One third of the gallon of water added initially was retained in the sand after the dozen or so flushes.  (Yes, I lost count.)

 

I'll try to get a sieve analysis done this weekend, so I have a more accurate Idea of the particle size distribution in my sand.  I've linked some pictures above, but I've also included the same links here:

 

http://aquaponicsnation.com/forums/uploads/gallery/album_147/gallery_4554_147_155366.jpg

http://aquaponicsnation.com/forums/uploads/gallery/album_147/gallery_4554_147_476228.jpg

http://aquaponicsnation.com/forums/uploads/gallery/album_147/gallery_4554_147_642341.jpg

http://aquaponicsnation.com/forums/uploads/gallery/album_147/gallery_4554_147_2070752.jpg

 

The last shows the approximate scale of the sand in the beds, and you can see some of the shape and texture of the granules.  Notice the mica granules - they're the ones that often have a flat shiny face that catches the light.  These granules are the same size as the silica, but they are constantly releasing flakes as they are worked, and from what I've read, they tend to delaminate as they absorb water.  What this will mean in the long run is uncertain to me.  While the flakes over time will likely tend to clog the system, I'm hopeful this will be a minimal issue in the few months that this system is likely to operate.  If the mica decomposes chemically, it may provide a boost in Iron and Magnesium, which wouldn't necessarily be bad.

 

Another issue I'll face in the short term is remediating the carbonates left behind by my well water, which is very hard and was used for all of the washing.  Hopefully, the residue will not persist long, and pH issues will be dealt with before the fish are added.

 

More tomorrow.

Edited by MT Mind (see edit history)
mhaigh and ande like this

Share this post


Link to post
Share on other sites

Hi MT Mind,

 

Kudos to you for your efforts to source sand for your little system.

 

Don't worry about the impact of washing sand in high pH water.  If that's the only source of carbonate in your system it will quickly diminish.  Are you using rainwater for ongoing operation?

 

Gary

Share this post


Link to post
Share on other sites

Adventures today, so I didn't get anything done that I wanted to do, but that's life.  I won't be using rain water to any significant extent, though I'm sure some will get in from time to time.  We have a reverse osmosis unit for drinking and cooking water that can easily supply another couple gallons of water every day.  The fish tank will only have 17-18 gallons in it, and I doubt I'll need to add more than 10% each day to keep it up.  I know the reverse osmosis is pretty wasteful from a water conservation standpoint, but our rainwater is pretty awful.  I've collected rainwater here before, and it makes me sad.  A clean white bucket placed in the open, half full from a rain shower, will have a thin layer of mud at the bottom, a yellowish-brown tint to the water that never settles out, (I think it's cigarette smoke.) and a pretty rainbow oil slick on top.  I just can't bring myself to use it in the iAVs.

Share this post


Link to post
Share on other sites

Geez, MT Mind.....if my rainwater looked like yours, I'd take that as a hint that I needed to live somewhere else.  Do you live alongside a power station or a car manufacturing plant.....or something similar?

 

Gary

Edited by Gary Donaldson (see edit history)

Share this post


Link to post
Share on other sites

We're working on getting moved to central Texas, but it won't be until later this year.  We don't live adjacent to anything; we just live in the middle of the oil field.  This area is on the edge of the U.S.'s "Desert Southwest," so there isn't much plant life to filter the air, and the oil wells are always leaking.  The prevailing winds from the West occasionally bring in dust storms, but they usually just keep a constant supply of dust in the air.  Combined with the diesel soot and sulfates from the flare stacks that dot the landscape, it's not surprising the sky is a little more light brown than blue.  After the rain is the only time the sky ever looks clean.

 

We actually had some substantial rain yesterday, so it's nice this morning, but between that and some unplanned activities Saturday, I didn't get anything done with the iAVs.  :angry:

Share this post


Link to post
Share on other sites

First test run of the system this afternoon!  I may need a larger pump, but I think it will work.  Here are some pictures:

 

Patio iAVs Assembled

Patio iAVs Fish Tank

Patio iAVs Output Tee

Patio iAVs Drain Elbow

Patio iAVs Drain Flange

 

 

Here is also a link to the DropBox folder I have created for this, in order to hold videos and the original full resolution photos instead of filling up the forum server storage:

 

https://www.dropbox.com/sh/rrze0b32nugdzqq/AACRTTNchKS2zgdGxzdnLDN2a?dl=0

 

There is a video included there showing the system running, so please let me know if the link doesn't work.  The setup is pretty straight forward: pump in the tank pushes water up to the sand, drainage caught in tray slopes toward the homemade drain flange and returns via 1" PVC to the tank.  The tank is not completely full yet; it has two water changes from our indoor aquarium (10 Gallons) and another 5 gallons of RO water, which has been growing some duckweed while an air stone keeps it circulating.  Now I need to move the duckweed to another container, so I can cycle the system and add fish.  I added some aquarium inoculant to jump-start the cycling process, though the aquarium water probably had plenty of bacteria already.  I'll also add a distribution manifold to the tee so the water doesn't keep digging holes when the pump runs.

Edited by MT Mind (see edit history)
ande, GaryD and neighbor like this

Share this post


Link to post
Share on other sites

It's been a fun week, and I haven't had a full night's sleep since the last post, so forgive me if this makes no sense.  I'm not sure how my fish are still alive; I found out last night that the system water pH is at 8.2, and the Nitrites are at ~8 mg/L.  It turns out the API 5-in-1 test strips are not accurately reflecting the conditions in the system.  I have a Hanna Champ digital pH tester from back in the day that I dug out and replaced the batteries, but it was giving me 8+ while the test strips were showing ~7, so I figured the electrode had dried out and needed to be replaced.  It had been in storage for over ten years, after all.  The test strips also showed around 20 on the nitrates and basically zero on nitrites, so I wasn't too worried.  Since the test strips are quickly running out, I finally stopped and picked up an API Freshwater Master Test Kit on the way home and went through the series of tests.

 

Results: pH = 8.2 | Ammonia = 0.25 | Nitrites = 8 | Nitrates = 80

Sample was taken at 6:15 pm after the fish were fed at ~5:30 pm

Water Temperature at the time was 91-92F or 33C

 

Apparently the pH tester isn't dysfunctional, and I may need to do something to keep this from getting out of hand.  Unfortunately, since my readings were inaccurate before, I'm starting from now with my data.  I don't even know whether the General Hardness and Carbonate Hardness readings from the test strips were accurate now.

 

Since the first "test run" of the system, the pump has been cycling 30min ON and 90min OFF starting at 6:30 am and stopping at 9:00 pm.  The first 2.5" comet Goldfish, now named "Jinyu," was added the evening of the 30th and the second, now named "Iask Orga," was added the evening of the 2nd.  Feeding began Monday morning with a pet store food that is probably poop, and they are simply getting a few flakes in the morning after 7:00 am and in the afternoon after 5:00 pm.  They seem to be eating well, and haven't yet shown any telltale signs of toxicity or extreme stress, but we still elected not to feed them this morning to avoid adding to the nitrite levels.  I'm guessing I'm still in the middle of the cycling process, but at least now I know there's an issue with pH that may need to be addressed.  Hopefully the nitrification process will help bring down the pH.

 

I also added a manifold to the output, consisting of 10 - 1/8" holes on either side of the tee.  I may need to add more holes or make them bigger because the detritus layer isn't really developing yet, and I'm afraid the water is washing it down into the sand.  Here's a little video of the water flow on the sand:

 

 

The water isn't spreading out down the furrows yet, and my pump won't flood the bed in 30 minutes.  I timed the flow from the pump at that head, and it's giving 160 gph so in my 30 minute run time it moves 80 Gallons, which is four times the tank volume.  The pump flow can be reduced - it's running wide open now - and I can add holes to the manifold to soften the flow over the sand bed.  I've thrown some shade cloth over the fish tank to help cut down on algae, and added some temporary styrofoam covers on the beds to try to keep the sand temp down.  We've had high temps around 105F or 40C for a few days, so it's no surprise the water is warm.

 

Covered

 

I'm open to suggestions, and questions are welcome as always.  I'm sure I've left out and/or overlooked some important data.

Edited by MT Mind (see edit history)
GaryD likes this

Share this post


Link to post
Share on other sites

Those test strips are trash and newbie bait.  Only time I use them is if I run out of regent and am waiting for another bottle to come in.

 

 

Fish load is not likely enough at this time to give a significant amount of detritus.   Though it's likely the low fish load that saved your fish. 

 

The shade cloth will help with the temperature as well as algae.  The algae may have been processing the ammonia instead of your system cycling, so now that it's covered monitor for Ammonia spike as the algae dies off some.

Nitrite is less harmful in goldfish than say trout or other fish.  Goldfish are fairly tough, kind of like tilapia as far as enduring poor water quality.    A few tablespoons of salt without any additives will prevent/reduce effects of  nitrite poisoning.  

 

Some ice in a baggie will bring the temp down temporarily.  I found running a fan over the tank gives it an evaporative cooling effect, but you would have to rig up a better way to shade your tank. It also increases water replacement needs.

Share this post


Link to post
Share on other sites

Yeah, the resilience of goldfish is part of why I'm using them.  They're going to have less than ideal conditions in this little system until I figure out what I'm doing, and I don't expect edible fish from a 20 gallon tank.  I've run the gauntlet again tonight, and I'm starting to think I'm mildly color blind.  Since the color chart for nitrite only goes up to five, I diluted it yesterday to 1/2 and 1/4 strength to get it to register within the range, and at 1/4 it matched at 2 mg/L, so I called it 8 mg/L.  Tonight I did the same, but I also diluted to 1/8 strength, and it perfectly matched 0.25 mg/L.  That would actually give me 2 mg/L for the total, which isn't nearly as bad as I thought.  I guess I just can't tell the difference in violets at the high end of the scale.  Tonight's readings:

 

pH = 8.2 | Ammonia < 0.25 | Nitrites = 2 | Nitrates = 80

Sample was taken at 5:00 pm after 24 hours not being fed.

Water Temperature at the time was 89F or 32C

 

Any recommendations for bringing the pH down, or should I wait and see?  With a couple of $0.35 goldfish, I'm not going to loose any sleep over it, though I haven't had decent sleep for a week because of the fireworks every night, so it wouldn't matter. 

Share this post


Link to post
Share on other sites

The Doctor , recommends sulfuric acid as it can be utilized by plants. I've used muriatic acid as it was convenient and easier to get in my locale.

 

The pH is close to optimum for bacterial growth, so if I made a change at this stage it would be slow and gradual.

 

What I would do is get a bucket of system water and add a drop of acid and stir and see how much change occurred.  The system volume is relatively small, so it could change real fast on you , depending on the hardness.   I've chased my tail before , by getting impatient and it not changing, so added more than I should only to see it's now too low.   Patience is key when adjusting pH.

Share this post


Link to post
Share on other sites

Well, the initial biofilter has established; nitrites were at 0 last night and the night before.  pH is still at 8.2, so I suppose it's time to start getting proactive on that; it had dropped to 8.0 for a couple of days, possibly thanks to a top-up with the RO water, which consistently tests at 6.4 pH.

I still need more fish, I've only got five 2" - 2.5" comet goldfish at the moment.  I was going to pick up some more yesterday, but the store had a sign up saying, "Under Observation."  Hopefully, they'll get a clean bill of health soon, so I can get enough gunk to start flooding the sand like it should be, and maybe nitrification will be enough to pull the pH down a bit.  The water has been at 90F/32C in the evening for several days now, but I suppose that's not too bad considering the high temps have been around 106F/41C.  The water is also quite clear now, thanks to the shadecloth.

I've had difficulty getting an accurate read on the nitrates in the system, but I think they were down to ~30mg/L last night.  I have trouble seeing the differences between oranges and between reds on the comparison card, so I had to do three different tests at different concentrations in order to pin it down.  Nitrates were around 60mg/L earlier, but the tomato plants are growing now, so I'll need more fish soon in order to keep up.

GaryD likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now