Backyard Aquaponics
A place to discuss aquaponics

Hi everyone. I have been passively absorbing aquaponics information for years and decided to build a small test system around large 30 gallon ice chests, (I have like 12 of them spare)

I started by buying fish. Mistake. One big catfish gorged on goldfish, then got cold at night, couldn't digest them, and died the next morning. That's my theory anyway. I put catfish #2 into my hydro set where he would be alone and better aerated. I left goldfish in tank#3 with a bag full of organic material and ducked from a local pond shop. (isolation/algae culture). The goldfish seem to eat algea, but many have died. I expect the population to reach equilibrium. I'm not cleaning dead goldfish out of tank. This is my aquatic compost pile I suppose.

Hydroset:
42"x42"x7" tray with sterilized (waste of time) lava rocks sitting on top of 3 ice chests. 1 is just a spacer. The other two I have dubbed tanks 1 and 2 though they are connected by a 3/4 inch pipe. I worry about my caulking feeling squishy inside.
I poured the catfish water out into growbed to seed microbes because I know they came from another biofilter system. I moved catfish #2 to a separate tank #4 but he jumped out and killed himself last night. I figured the micro horde can grow faster than plants, so now I'm focusing on just getting leafy greens rooted in the gb.

Now in my fishless system I have added Dr Earth Nitro Big 7-2-2 with prebiotic (c) [that probably is marketing speak for molases], and 3 cups of Dr Earth Kelp Meal which did not readily disolve as expected. It's also got lots of microbes in it. So the kelp meal should provide vigor and micronutrients and micro horde to the gb and the plants should all get fed by the nitro big. Meanwhile algea should grow and whatnot, and eventually I'll add any fish that survive my inexperience. After fertilizing last night, pH was 6.5, TDS 785 ppm, 26.0 °C

The plants seem good. My lettuce seeds are sprouting fast. But I worry that my ph constantly climbs. It seems to want to be pH 8 and plants start sucking amonia a at pH 7.5 or so, which is bad, and so I took catfish#2 out so I could radically adjust pH without hurting him. But the pH climbed overnight without his help! Again!

Now I'm reading pH 7.7, 777ppm, and 26.8°C

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Hi and congratulations for the start..

I was interested in the use of the ice chests.. are we talking about domestic electrical appliances, or plastic insulated boxes..

Just concerned for possible metals that may be used..

Photos will help folk visualize your setup..

Square tanks present.problems for sediments etc and. I wonder how the 3/4 tube would work..

Peter
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Hi J, welcome to the forum. Try not to get discouraged by early failures. I agree with buidoi on the pictures, there are some really knowledgeable people here and they will point you in the right direction of they understand your system better. Now here's my .02 as a caring yet less knowledgeable person. Are you adding any aeration to your system? That is definitely important in small tanks, try adding at least a small aquarium air pump. I mention that because, unless you're post dating this thread, I'm pretty sure the catfish didn't get cold here. I would remove any dead fish as well. What type of caulking is it that your concerned with? Personally I avoid caulking where possible it doesn't usually last. Lastly, have you considered stair stepping the tanks? Then just gravity flow through the drains and add a small fountain pump to recalculate as a constant flood system. Anyway stick with it and have fun!

Some pics:

https://drive.google.com/file/d/0Bwg6IT ... cslist_api

My tests show that my lavarock is actually alkaline, I soaked some in vinegar, no fizzing but the control soaking in tap water was pH 8.0. I washed the vinegar soaked rocks thoroughly and now they soak in regular tap water at pH 4.5. I might not have got all the vinegar out tho so I'm boiling them presently and will test again with fresh tapwater.

Geeking out

Even after boiling lava rock for an hour (till completely dry) Then roasting in hot pan for another 30 min, pH of tap water in rocks was 7.7. Regular tap here is 6.5. I would like to buffer against the alkalinity. I have seen you tubers with oyster shells in cheesecloth. But their rocks might have been acidic. I will research but am open to direct suggestions if you have any.

The carbonate buffers would help with acidity but wouldn't do anything worthwhile for your situation. There might be something you can do with phosphate buffers which buffer to 6.5 .

I would just adjust the top up water with HCl to a pH of 6.5 (and then let stand and adjust again if needed) each time you top up for a bit. Even without doing that, the pH will eventually go down because of Nitrification. I used lava rocks and had high pH for about 2 years but it eventually came down. I didn't use any acid this was done with only the natural processes of the AP system. Probably would have been faster but I use light fish loads. By the way I use oyster shells under one of the outflows to keep the pH up now.

Cheers

J, lava rock is a good choice for media. Try searching "scoria" on the forum. I use the viagro branded black lava rock from the big home improvement store. It does seem to buffer a bit, but the system will eventually even out. Muriatic acid seems to be the "go to" for lowering ph in ap. Just take small steps if you still have fish in the system. I would suggest you get your infrastructure sorted out then do a fish-less cycle with the time we have left in the summer growing season. In the mean time read the "IBC's of aquaponics" and the "pee-ponics" thread. It might be a good idea to sell some of your "spare" coolers and invest in an ibc, something to consider at least. Read all you can, troll Craigslist for good deals, and by all means don't give up.

Oops You beat me to the post Scotty

Ok so update:

If you saw from the pics, my water is hot with nutrients to Jumpstart the plant growth. I'm pausing the fish for now. Used HCL to beat down the pH and got it somewhat stable. Now I've got runaway acid crashes. I've been fighting it with baking soda and failing. Tonight I'm going to try the oyster shell idea. Supposedly they won't disolve unless the water is acidic and so they'll fix a floor to my pH somewhere. Any guesses as to where?



Maybe I can add such a product to fix a ceiling to the pH as described, ideally the pH would always stay between 6 and 7, with the shells disolving when it gets lower than x and the (product name?) reacting when it gets above x... and in a perfect world x=6.5

Slow down a bit, too many changes too fast.

My guess is you've used up all the buffering capacity of your water - hence the pH crashes. Baking soda is probably not the best thing to use because of the sodium http://www.ncbi.nlm.nih.gov/pmc/articles/PMC139373/.

When you put the oyster shells in make sure they are in a bag you can remove (I've also used crushed coral for this - works the same way). They will add buffering capacity in the form of carbonates but it's possible to overdo this. They'll also add calcium. When the pH is around 6.8 pull the bag - the pH will probably go down and you'll have to repeat the process - reinsert the bag when the pH gets around 6.2. If you can't manage to get the pH to go back up, that's when you need something more powerful than the shells. Potassium bicarbonate (KHCO3) or Potassium Hydroxide (KOH) would be my suggestions since they supply potassium. The bicarbonate will also help with buffering while the hydroxide doesn't but is a strong base (use appropriate handling precautions) and will raise the pH. Calcium Hydroxide (CaOH) can be used as well but will supply Calcium instead of Potassium (it's good to alternate for a balance between these two elements)

Since the baking soda isn't getting the job done, the KOH or CaOH may be the way to get the pH up. Then add the carbonates to maintain or slow the pH going back down (just remember to pull the bag if it goes up too much)

The order from least potent at raising pH to most potent is as follows
Carbonates, Bicarbonates, Hydroxides

Hope this helps

The shells seem to be working. Water was acidifying at -0.5/day and once hit 4 (!) Overnight. Since I added the shells pH hasn't dropped below 6. They're in the plastic net bag I bought them in. ~40 half shells in the 60 gal tank.

Very curious if there is a similar inexpensive (and organic?) Substance that will disolve and release h- any time pH gets above 7. Both shells and that stuff (if it exists) might make pH problems a thing of the past and get me that much closer to adding fishies.

Not willing to risk killing even goldfish with my ignorance again.

There are no magic bullets that I know of . Some people may strike a balance that works though.

Nitrification is going to push down the pH so really you only need to find a way to adjust upward a bit (like the shells). The more you feed the more the pH goes down because of nitrification. I can sometimes go a long time before checking the pH and other times it needs doing almost every day. Usually the fish behavior is a tip off, sometimes it's other things like the presence of algae. If I had lots of fish, I'd be checking it a lot more often.