Backyard Aquaponics
A place to discuss aquaponics

Backstory:

Built this constant flow system two months ago, managed to get it to fully cycle to 0 ammonia, 0 nitrite to 80ppm Nitrate in a few weeks using a Nitrogen-Cycle in a bottle product. 30 small gold fish. Fed fish flake food and insect bites (sparingly as a treat). The grow bed is rectangular in shape, lined with a pond liner. Water enters into one side, drains on the other. The bed is filled with expanded clay pebbles. In the bed is a series of white plastic (HDPE[2]) buckets (holes drilled to allow water to pass through) which are also filled with clay pebbles which house the plants (cannabis). There is 4 large air stones submerged under the clay pebbles, and 4 submerged in the fish tank. Plenty of air in the system.

Once the system cycled the plant growth exploded for about 2 weeks, then basically stopped. The PH seemed to stay high 7.6-7.8, I figured this was the problem. I drained most of the water from the system, removed all of the gravel I had in the tank, and waited, expecting the PH to go back down. It has not. Many more almost complete full water changes, including changing out all of the clay for virgin clay (although dust rinsed off) has still not managed to bring the PH back down. As of a test yesterday, the nitrogen cycle is still working.

My municipal tap water is 7.4ph/50ppm from my garden hose. I use a dechlorinator/dechloraminer product to make the water fish safe, this water sits in a small tank which is auto topped off/fed to the system via a float valve.

My PH reading is confirmed by a recently calibrated BlueLab Combo Meter and PH drop test kit.

Can someone PLEASE tell me why this isn't working anymore? I REALLY wanna get this thing going again. My wife was recently diagnosed with cancer this year and she needs these plants (has a prescription) to help with the constant onslaught of depression and nausea that her medication causes her.

Thanks so much for reading and responding.

First of all,I'm sorry to hear about your wife.Hope she recovers soon.

Sometimes during cycling & just after,the PH can go up.You say the tap water being left in the tank with the float valve (at least 24 hours) is showing 7.4.
7.6-8 could just be down to the newly cycled system.If they clay was got from a shop & it's actually meant for growing plants,it's unlikely that's the problem.
The KarbonateHardness (the buffer) is keeping the PH in place & holding it there.It's not a bad thing but after a PH of 7.5 some of the nutrients will become unavailable.

You need to bring the PH down.A lot on the forum use acid to bring the PH down but you could use distilled/de-ionised water too.

Is there any wood in the system?

First remain calm. Never freak it.

Second only do water changes in emergencies IE fish are going to die.

About the only thing to bring down PH is time. Takes my systems about 7 months for PH to come down to where I like it at about 6.5 when I rebuild them. I too use hard city water and clay pebbles. Every water change or top up only adds to the PH. Best thing is to collect rain water and top up with that.

I have tried adjusting water for PH before adding to the main systems but I swear it wrecks havoc and drops the whole system. My city water is about 8ph. Takes about 1ml of acid to bring my city water to 6.5ph. My thoughts on it are that the acid isn't fully neutralized and the chemistry works a lot different than my non chemist mind can comprehend. So I do everything in my power to avoid that situation.

I am guilty of using dechlorinators in an emergency but due to the fact the bottle says not for human consumption I would avoid its use. We don't know what those could do to us. If its just chlorine in your water then let it sit in the sun for a couple days. 24 hours is all it takes but I like an extra day. You can use vitamin C for same day use. Crush the pill and mix in. One pill will dechlorinate a bathtub. I put about half a pill per 10 gallons because it hard to eye ball and measure. Let it sit for an hour or so and use.

Next thing. High Ph will cause nutrient up take issues so foliar feed with seaweed extract every week or so while you are above 7ph. And look for a high PH iron supplement. I use the DTPA Iron it is expensive but you can get it off amazon. It will work above 7. I put a table spoon every two weeks because this stuffs expensive and I am stingy with it. My homework says I should use more but I dont see any signs of nutrient issues so I role with that.

Next issue.
Plants grow in cycles. One cycle is the greenery grows. Then it stops. Normally when you stop seeing exploding growth means the root systems are growing. Roots grow to support the plant then the plant grows to the max its roots will support. It cycles like that until fruits.

Also I would switch the food. Flake food doesn't have much extra nutrients for the plants. Luckily gold fish grow fast. Those comet gold fish will be 4 to 6 inches in a year and max out in 2 years at 8 to 12 inches. I keep telling my wife not get gold fish but every year a new one shows up in fish bowl and she doesn't know how it got there. It never fails and always ends up the aquaponics system by the end of the year.

For food use a pond fish food or aquaculture food. It will have more nutrients than the fish need so the plants can have the extra.

Then as after thought:
Don't sweat a high PH. I like my ph 6.5 to 7. 7.5 isn't that bad is on the borderline of too high and might only cause minor nutrient problems with Iron being the main issue. There is a chart some where on here showing the nutrients and PH ranges.

Sorry to here about your wife. My wife also has cancer and tumors and uses cannibus. I cant grow it for her though because I am still on active duty. Maybe in 4 more years when I retire.

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I appreciate the support. The water sits in the top up tank for many many days before it's completely empty. I believe I have enough water in the top up tank to keep the system at max water level for many weeks at it's current growth rate. It never had an air stone in it until last night though, that was a recent addition trying to figure out what the issue is.

If I have hard water, wouldn't that show on a TDS reading? At 50ppm tap water, isn't that basically pure water? There is no wood in the system. The system is made out of wood though, but no water touches it. Thank you for replying!

I have done Aquaponics outside before, I don't recall ever having these issues, perhaps that was due to using well/rain water though.

I'm also confused, isn't a system "fully cycled" once the system has the ability to convert ammonia into nitrate and the nitrites read 0ppm? What other bioactivity needs to happen for the PH to begin to fall? Now that I have an air stone in my top up tank I will stop using the dechlorinator product and see what happens. I'll check into the iron supplement. I do currently have concentrate seaweed powder, I'm hesitant to use it in the system because during my tests in a small cup of water it raised the PH to 8.3. I will spray it on my plants and hope that helps. It also seems like I should just bite the bullet and buy ANOTHER round of test kits that will test for hardness. I sometimes feel like I'm just lighting money on fire with this system lol.

Would a gold fish PELLET food qualify as a pond food? Can you recommend any fish feed that is available to me in Canada?

Thanks so much for the support. If your wife also has Cancer you definitely understand the urgency and anxiety that I'm experiencing. I'm really sorry to hear about your wife as well. How is she holding up?

The TDS meter would read everything that's in the water,most things would add to the PH.But the buffer (carbonate) would be holding the PH in place,the TDS meter can't tell the difference between all the different things in the water.
It sounds like you have high KH carbonate hardness & low GH general hardness.Ideal!.
You just need to bring the PH down a bit.
The Ph will fall through nitrification when the buffer is running down or has been used up.But remember that everytime you top up,you'll be adding more "stuff" via the top up water to the system.Everyones water is different so no one could really say when yours will fall or if it ever will.

The reason I mentioned the tank is to find out if you've measure the PH after the water has been sat for a while.

How long has the system been up & running?.There might be an actual nutrient deficiency/ies if it's a "young" system.I should have asked in my 1st post,have the plants been showing any signs of deficiencies?
And fish food is important,flakes aren't good for aquaponics.
How many plants do you have to the 30 fish?


I'm sorry to hear that.I hope she recovers soon too!

There is 10 plants in it. The smallest are like 3 inches tall, the biggest are around 12 inches. It's definitely showing some deficiencies since it stopped growing, but not much. Lower leaves going yellow, a bit of blotchyness here and there, but nothing major. It also seems like the roots are still growing and have not stopped growing.

As for the "buffer", what is it that you mean by this? You are referring to the chemical in the water that is keeping the PH high? Is the solution to add "way" more fish? That would put more pressure on the nitrogen cycle which should keep the ph lower?

The others have added most I can think of however I will add a couple of points if I may.
Lower your top up water with hydrochloric (muriatic) acid before adding it to the system, this way you can effectively set your desired pH. For the pH to drop naturally there needs to be more nitrification going on than is currently happening, so...
Adding seaweed emulsion will give the plants a helping hand plus additional ammonia sources like fish emulsion in small doses to boost the plants also and really see how cycled your system.
Aaaand lights. Are you using lights? Are they good quality?
And please stop adding unnecessary chemicals, the whole idea of AP is to rely on Mother Nature, you seem to be in a rush and AP also relies on patience. If you are looking for instantly creating a growing paradise perhaps look at hydroponics.
And yes pond food. I have little experience on this side, I used koi feed when I had goldfish and koi but they all kept dying so I gave up.
I hope both your wife and RC’s wife’s health improves.

Thank you for the kind words. I'll consider everything you've said here.

I am very familiar with Hydroponics, I actually switched from hydroponics to Aquaponics because I wanted to utilize "natures automation" so to speak. I've done Aquaponics before outside a few times and had immense success with it, but now I'm starting to think it was beginners luck of some sort.

The lights are T5 CFL 4000k, not exactly amazing, but they've worked well before when I used hydroponics for the vegatative phase.

While I've got ya here though, I'm curious, quite a few Aquaponicists keep telling me that it takes "time" for the system to establish, as long as 6-7 months. What do you mean by this? Is there more to this process than the nitrogen cycle taking ammonia and turning it into nitrate?

I have ZERO issue with being patient, I just don't wanna sit around and do nothing if there is something I can do to fix it. If I knew 100% right now all I had to do was just be patient and maintain the system I'd happily do it. I just don't wanna see myself in 6 months with the same issues.

Very much appreciate your chiming in here.

Hi mate, from my understanding and I may be wrong, I frequently am, the bacteria colonising the system is constantly evolving. For years my system always had high pH and I used to wonder what folks were on about when complaining about low pH then one day I saw the fish weren’t eating and I checked the pH and it was in the 5’s! So it took a couple of years for all the carbonates to be used up and now I’m continually adding lime to the system to stabilise it.
Aged as my system is now I never see ammonia or nitrites and haven’t checked for nitrates for ages either.
Even when a system is mature it is still building, the nitrogen cycle is always cycling.
I have no idea on lighting but most ‘plants aren’t growing’ threads are indoor systems with lighting issues.

Aye, I've been reading, apparently there is many other forms of bacteria and bacterial relationships in the magic of AP other than just two we're familiar with, nitrosamonus and nitrobacter. And they take a while to develop their complex relationships.

The lights definitely work, I've grown with them before, many many many times.

I've started putting in PH down, and will be switching to rain water or getting an RO machine in the interim. Already seeing the plants turn around. Thanks for chiming in.

The buffer is what holds the PH in place.It's a good thing,PH fluctuating too fast will hurt the fish,bacteria & the plants.
And no,you don't need more fish.If one was to add too much fish,it would over load the bacteria & probably have a huge Ammonia spike.

After you've run a system for maybe a year,there will be a "nutrient bank" built up (mature system).If you are seeing 0Amm,0Nitrite & measurable Nitrate,you're ok.Just keeping feeding the fish decent food.

T5s & CFLs are pretty good (if they are actual grow lights),I use them.Only "weak" fruiters will produce fruit with the amount of bulbs that I've got.If you go for LEDs,make sure it's the real ones.But it'll cost you.
When your plants start budding,what are you going to use?HPS bulbs?.

I'm still sure most of the problems are down to the PH.Lower it (easy in your case) & feed the fish good pellet food.And let us know how everything is getting on.

Price of LED have come down a lot. Think I paid about 200 bucks for mine on sale. My system is on the porch of my apartment so it gets indirect light and shade. Works great and been going strong over a year. Still haven't been able to get tomatoes to fruit but peppers, squash and cucumbers fruit like crazy.

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Yes, I've been manually lowering the PH slowly with drops, will eventually switch to an RO system or Rain Water. The plants are already responding well. I might add some seaweed extract back into it. Seaweed also contains some iron right?

When I lift the buckets out and put them into their flowering chamber thing, they will be under some COB Leds .I also have HPS but I thin the LED overall are better.

Thank you for your help!

That's a bargain!.I wish I could find them at that price.

Be careful with RO & rain water because they have no buffering capacity.The PH can fluctuate fast.
A suggestion might be to lower your PH to 6.5-7 now & then top up the system with your tap water.That way the buffer from your tap water might hold the PH in a good place.You'll need to test it and see if that works.

Depends what one/brand you have.I know there's a maxicrop version that has it.