Sunday, October 24, 2010

Day 2 - Got my fish!

Picked up 4 female and two male tilapias, all close to fully grown, and two fingerlings. Could not get my hands on any more fingerlings unfortunately, but it's a start. The place I got them at is no more than ten minutes from my place, so I was able to transport them in some old plastic buckets without the need to worry about oxygenation.

I also adjusted the height of the upsteens on two of my grow beds. The water level just wasn't reaching the roots, and upon inspection, I realized the level was well below the recommended 5cm depth (from gravel level down). The plants in the bath tub were fine, as the water level there was reaching about 5 cm below the top of the gravel.

My PH level got back up to 8. It must have something to do with the gravel. I squeezed one lemon into the system and will add one per day until the level gets below 7. The high PH shouldn't hurt the fish, but it definitely won't be good for the plants. This will all be academic once the system stabilizes, but for now, I'll just have to keep an eye on it.


  1. Hi Patrick, nice job so far.

    Just curious as to what you know about Tilapia. I don't think I can grow them in Missouri without some sort of heat in the winter, which is obviously not a problem for you, but do you know what they are able to tolerate as far as temperatures, both high and low?


  2. Actually, I think I answered my own question:

    These guys are very close to me and grow in buildings. I would need to heat the space to at least 60 degrees in the winter.

    Still do-able, just not as easy as Costa Rica!

  3. Ready - nice to see you here! Yes, they are a tropical fish and need warm water. Don't know what would happen to them in cold water, but apparently it is not good. I don't know if going through the trouble of heating the water is worth it, but it may be. Tilapia are extremely hardy, can live in almost anything, and reproduce like crazy. I'm sure there are cold-water fish suitable for aquaponics, but I do not know what they would be in MO.

  4. Re: pH Is it a limestone based gravel? If it is, your going to have to replace it, because buffering it with an acid will just dissolve it over time. Look for a gravel that is Quartz-based pebbles like river rock; limestone doesn't break down into rounded pebbles.

    Also, it might be your concrete walls in your fish pond leaking the lime into the water. This will be an easier fix as you can just paint it with a fish-safe sealer. You can typically find this in online stores that supply Koi pond products. I'll see what I can find and send you a link.


  5. Damn - I hope it's not my gravel. Gravel here comes from riverbeds - would that rule limestone out? I'll check the product I used to seal my tank walls- that's definitely a good candidate.

  6. I don't know regarding limestone in riverbeds. I wouldn't think you could necessarily rule it out, unless it is fairly rounded pebbles. Maybe try taking some gravel, cleaning it, and put it in a bucket. Test the pH of some water and then add it to the bucket. Check the pH again in a day or so and see if it changes. if it doesn't, then the problem is probably with the cement/concrete tank.

  7. Right on, Jeff. You read my mind. I'll be running the test this weekend.

  8. PS: I did find out the gravel comes from a riverbed, but as you said, that may not rule out the possibility that it is causing the high PH.

  9. Hi Patrick. I presume you are in NZ? Where did you get your fish from? I'm looking to build a system in the new year. Rgds Stu