Backyard Aquaponics
A place to discuss aquaponics

Good day everyone,

Im a covid19 AP newbie and would appreciate your input please.

It seems like I am experiencing some nutrient deficiencies judging by my Bokchoy and choysum. Basil seems to thrive as I understand that it is not affected by pH. I suspect K or Fe deficiency.

Currently foliar spraying with Mg,Fe & Seasol mixture.

pH 6.4
NO3 40ppm
NO2,NH4 0
1tbsp daily of Fish feed (koi spirulina pellets + some pellets are got from livestock shop)

FT 180L, 2 half barrel (1 raft + 1 media bed), RFF. 22 tilapias (1/2lb each)

pH was at 6, so I had added
1 tsp Mg
1 tsp K
1 tsp Fe
1 capfull Seasol
which raised it to 6.4. Growth was much better after, but leaves still show deficiency. I wish I had KH tester but using the API kit.

- Could someone inform me on how to correct deficiencies? (supplement ratios , how long to wait for buffer to show pH rise, monthly buffer to avoid deficiencies, am I not adding enough K or Fe?, anything I may be doing wrong?)

Cheers!



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From what can be seen in those pics I'd suggest, with a great degree of certainty, that you don't have either a Potassium nor an Iron deficiency.

What is it that you are concerned about?... Is it just the pale green across the leaves of the Bok-choy?

Are all the fines being well filtered from the water prior to the DWC bed?... Is the water in the DWC bed aerated?... What are you doing with the solids collected by your RFF?

I'd also suggest that planting Kangkong directly in gravel grow beds may be something that you will regret in the near future.

Also, 22 x 1/2 pound Tilapia, or any fish, is a MASSIVE amount for that system, in regards to:

(a). Safe fish stocking capacity, ie: Fish to Bio-filtration (wet gravel) ratio.
(b). Fish stocking density, ie: Fish to water ratio.
(c). Fish to plants ratio.

I would keep a very keen eye on your Ammonia and Nitrate levels, as I suspect you may be about to run into issues. I would also watch the water temp and pH as your spring starts to kick in over there, as the higher the pH and/or water temp, the less Ammonia it takes to harm your fish.

Indeed (*embarrassed ) I am in the process of building a second little system to split the fishes. Yet I know that 8 fishes is the maximum I should hold in my systems. Do you have other ways of keeping the fish happy outside of a system perhaps? I'm waiting on hardware stores to operate in my city to do an upgrade with ibc. Hence I don't want to part ways with the tilapia.


What should one watch out for in terms of Temperature please?

Thanks for taking the time to write

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You are only feeding 11 pounds of fish 1 tblespoon a day?

Pour guys have to be hungry they should be getting 3 to 5 percent of their body weight a day. At 11 pounds that's they should be getting about .33 pounds of food a day.

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22 juvenile tilapias. Not pounds:)

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Btw, I replied to your questions by copy&pasting your message with my answers in between. Thanks again

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For the temperature reference: as temps and PH increase ammonia becomes toxic. Ammonia has an inoized state and unionized state. Ammonia is toxic to fish but ammonium is less toxic.

Ammonia test kits normally check total ammonia. The API test total ammonia. There are some out there that will test the toxic ammonia though. My system normaly has trace ammonia. Less than .25 PPm cross reference the chart for temp and PH and only 12% of that .25 is toxic. Well within safe limits.

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Thanks! How did you get to be so knowledgeable about AP? My Ammonia shows 0ppm as well as NO2.
How do you supplement your system and frequency btw?
I'm wondering about the ratios per FT if you don't mind?
Do you alternate K and Ca?
And is Fe once a month?

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Owe, I think your plants look fine and your water is good for now. I would only adjust PH with a potassium supliment and calcium supliments alternatingly.



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I have actually been doing aquaponics for several years. YouTube, Google, here, North America Aquaculture South Regional and NAACR (same thing but Central Region), Florida State University ext are great sources of articles. You really want to learn something take a look at Bright AgroTech on you tube, then read the comments. Because you will learn something from the video and someone will contest what Doc says and the next thing you know you have read 3 different scholary articles and trying to develope your own opinion. You gotta start somewhere.

Anyways, I don't really add anything beyond. Calium Hydroxide or Potash alternatingly to adjust PH when and if needed. I keep dolamite and crushed egg shells on hand for the system really gets cooking and I need to buffer the PH. I toss in about a tables spoon of iron every two weeks. It was more of watching my plants and adding than really math. Some articles say about a table spoon per 100 gallons every so often. Feed has the majority of what plants and fish need. Feed is just defiencient in Potasium, calcium and iron because it only has what the fish need. Remember Iron comes in several forms, match the form to your PH.

There are different ways to do stocking. I try to hit them both BSA and water volume. Water volume is 1lb fish to 8 to 10 gallons of water. The BSA is what is really the filter for your water. In my notes I have min of 25ft squared of BSA per a pound of fish and recommend of 100ft squared of BSA per pound of fish. I actually stocked my tank heavier. i sized the fish tank to hold the amount of fish I wanted to grow then I added enough grow bed media and filtration to get the BSA high enough.

Then there are feed rates per BSA, I don't really follow that one too much and it confuses me. I just feed my fish to satiation and clean out the uneaten. Experience has taught me to control feed to control ammonia.

There are no hard set rules. Takes someone's starting point and learn.

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Yes you're right. Got to start somewhere.

You've given me lots to think about and improve on. Thanks for your help. You've saved me lots of time and headaches.

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Regarding stocking density "1lb fish to 8 to 10 gallons of water". Is the 8-10 gallons of water FT volume only?

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Fish tank volume. Fish need room to swim around in. That's not a hard set rules and experience may dictate different.

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Thanks. I got slugs fondling around my raft since last night. Its been raining.

Take care

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Hi guys, is it normal to have to buffer the system weekly as pH drops to 6.0? Or is it something to do with water hardness? Cleaning out RFF and small particles filter biweekly?

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