Backyard Aquaponics
A place to discuss aquaponics

You will probably find that the shell grit will buffer to 7.6 and stop there (self regulating is kinda nice) I've pretty much filled my whole system with shells though and the iron is all locked up so I have to foliar feed all my plants iron.

Anyway, welcome back, we've missed you. A little fish watching to sooth away the stress of UNI.

Thanks Jaymie and TCLynx
TCLynx, is that because iron doesn't dissolve at high pH?

First readings after the fish went in (after about a week):
pH: 5 (way down!!)
NH3: <0,2
NO2: 0
NO3: 0,5

I didn't believe the pH reading, so I did it twice, but it really does say 5.. So I put the end of the pump hose in a cloth full of shell grit (like I should've done way earlier), and the water coming out of the siphon is now at 6 so the water will slowly get less acidic.

Does anybody have any idea how the water could get so acidic in just a couple of days? It hasn't been raining and as far as I know nothing got into the system apart from a few grams of fish feed and possibly a little soil residu from a couple of plants that I put in the GB..

Anyway, all eleven fish are still alive and they look just fine. They're very shy, but they do eat if you feed them (they're still so shy that they only come up if they can't see you, though).

I've planted some small onions in the GB, and some strawberries, and some beebalm (my favorite flower). They seem to be doing fine. I don't see much growth, but that must be because I'm not patient enough

Early this morning the pH was at 6. I put the bag of shell grit in the pond (instead of on top of the growbed) and the pH is now at 7.

The autosiphon was acting funny so I tweaked it, and finally decided to remove the U-bend. The growbed now takes 9 minutes to fill, the autosiphon then lets through the same amount of water as the pump puts in the growbed (equilibrium) and then any movement is enough for the siphon to kick in. With the outer pipe loose, it can take 2-15 minutes before the siphon kicks in, but I tweaked it a bit and now it kicks in after 2 minutes every time. The growbed then takes 3 minutes to drain, and it takes another minute or so for the siphon to shut off again. Which makes a 9+2+3+1=15 minute cycle.

The system:


Siphon (starting, kicking in, sucking air):


Feeding time! Well, they only came up to eat because they didn't see me.. It's a horrible picture, but if you look well you can count all eleven fish.

I look forward to seeing this system overrun with veggie growth! From some reason those grooved boards really make that system look nice. Nice enough that any of the lawn and garden freaks down here would love to have on in their backyard.

Thanks, Dan

Wednesday 7th:
pH 7,0
NH3 0
NO2 0
NO3 0,5

Saturday 10th:
pH 6,5
NH3 0
NO2 0
NO3 0,5-1

The water was turning slightly green, but this morning it was suddenly clearer than ever! The water used to be in the sun for much of the day, but yesterday half of it was in the shade from a parasol, though I don't think that could've suddenly killed all the algae..

The pH has dropped to 6,5 again. I'm considering adding more shell grit, but I don't want an excess of calcium in my system (or locked up iron like TCLynx).. I'm still looking for potassium bicarbonate but haven't been able to find it anywhere.

Ammonia and nitrite are at absolutely nothing (even though I'm probably overfeeding the small fish) and nitrate seems to be increasing. It looks like the system is cycled for this amount of fish


In Gokul's thread, Caribean-grower said I have 2,4sqm of growbed, so I'd need at least 150g of fish food per day. I'm only feeding 3 grams, 1-3 times a day at the moment because I'm guessing the fish at about 10g each and I want to feed them about 6% of their weight a day, so I'm nowhere near 60g per sqm.. At 6% feeding, I'd need at least 2,5kg of fish in my system to keep the plants happy!
I could get a couple of older koi or other bigger fish, but I'm afraid they'd eat the small fish I have now.. And fish food is quite expensive, though that would just make me figure out how to make better fish food myself sooner..
The easiest and cheapest way to supply the nutrients is probably humonia, so I'm saving 500ml plastic bottles.. I'm letting the pee age for about a week. I'll test the pH after next thursday, and from then on I'll probably dose 250-500ml a day (starting slowly to see if the bacteria keep up).


Siphon was still acting funny, so I added a single 90 degree bend. It's on a very reliable 17 minute cycle now.


My system has the following veggies:
- A cherry tomato plant (growing well, showed its first flower today)
- Four lettuces (also growing well, they're the ones under the green pyramids)
- Basil (too old, almost flowering)
- Strawberries (doing well, also put in some with flowers today)
- Onions from sets (growing lots of roots, some are already coming up after a few days)

Also the following ornamentals:
- Beebalm (two varieties, both doing great)
- Lupin (doing great)
- Daisies (they were dying before I put them in, but they're doing great now!)
- Sunflower (almost died after transplanting but seems recovering)

And today I sowed:
- Beans
- Corn
- Lettuce
- Beets
- Radish
- Spring onion
- Watermelon (which is rather optimistic in the Netherlands)
- Basil
- Tomato
- Leek
- Some flowers that I don't know the name of


Sorry about those horrible pictures, might replace them when I get the chance.

Tomas,
You would probably be safe adding more shell grit in a bag. That way you can adjust the amount you are using if you see signs of iron deficiency. (Remember that my system is literally full of shells as they comprise about 50% of my grow bed media.) The plants and fish like a fair amount of calcium too. The shell grit is probably the cheaper and easier way to control your pH rather than needing to add potassium bicarb on a daily basis. If you can easily get some potassium bicarb it might be handy to add some to help with potassium though.

Go slow with the humonia additions. Like starting out adding less than 50ml or something since the system will have to cycle up to the new load and you don't want to kill what fish you do have.

Good luck with it. I always thought that was such a sharp looking system, I'm glad it is back in use!

Thank you very much, TCLynx, I'm honored.

I live near a beach (15 minutes by bike) so shell grit is indeed the cheapest option, thanks. (I should've got this shell grit at the beach too, but I guess I was just lazy and bought it in a shop..)
And also thanks for reminding me that I don't want to kill the fish; I'll definitely go slow with humonia and test how the bacteria are coping, like you did in your peeponics thread.

Make sure to wash the shells too, someone didnt and killed some fish...

Thanks for the warning!

Looking very good Thomas.....

Quick question.... Are the shells from fresh water or ocean? Would it make any difference?

city, dont thinkit would make too much of a difference, they're both CaCO3

Tom, man that is a NEAT looking system, well done again!

and you've provided such a good stream of photos from start to end...........almost time to put it in the "completed systems" section

Cityfish, the shells would be from the North Sea if I got them at the beach. The shell grit I use now is from the store and also saltwater.

Thanks Steve, hopefully the cycling doesn't take too long!

NH3: 0
NO2: 0
NO3: 0,75
pH: 5 or lower!!!

pH dropped again, so I added the remainder of the 4kgs of shell grit I got from the store and about 300L of tap water (pH=8,5, if I remember correctly). An hour later the pH was at 6,5.

The fish are looking just fine; they ate their food this morning and all eleven of them are swimming around like usual. The biggest ide is starting to get a bit of red on its fins (some adult ide have red fins so I don't think it's a disease). The plants are doing great (the onions and the tomato are suddenly going for the sky!) and the water is exceptionally clear and doesn't smell (despite the low pH).

I have no idea what's causing the sudden pH drops; there hasn't been any rain and the only thing going into the system is a couple of grams of fish food (still no hummonia).. I don't think my test kit is giving the wrong results.
I'm concerned about the fish (though they're looking just fine), but also the bacteria. I hope I didn't kill them! There's still NO3 in the system, so hopefully I didn't.. Anyway, I'm definately not adding any hummonia for at least another week.

As far as I'm aware, there's nothing leaching into the system (and it hasn't rained for weeks).. Does anybody have any idea what could cause these pH drops?

5

Dont know what would cause such a large drop...

have you tested with another ph test? or tested your tap water (should be around 7)

is it possible that your test vial was contaminated?