In the barrel system I never quite let the pH drop that low but the bacteria are probably the cause. Sounds like the system is cycled to your current load. I do remember cycling my first system and thinking that my pH would probably never drop below 7 (the guy at the fish place didn't think that I would need much buffering with the well water we have around here.) But As my system was reaching the cycled condition, the pH suddenly dropped to 7 then the next day was in the mid 6 range and I added all the egg shells I had saved for my worms. I expect that if I had done nothing for a couple more days, my pH would have been below 6. As it was, the egg shells didn't bring the pH up high enough for my taste. I now have lots of washed shells in the system and my pH can't get below 7.6.

No need to go as overboard as I did, as simple bag or bucket of shells below your return to the fish tank should help you out and you can adjust the amount of shells in there so that your pH doesn't stay too high.

Steve, I tested the pH of the tap water (and it shows 8,5-9 like it should). Maybe you're right and my vial was contaminated...

TC, I added a bag of shells just like you said and it's kept the pH at 6,5 so far.

pH=6,5
NH3=0
NO2=0
NO3=0,5

The system seems to be cycled for this amount of fish; in fact, the fish don't seem to supply enough for the few plants in the system as the nitrate seems to be declining. Onions and tomato have been growing very quickly, and the basil and radish seeds germinated in only a couple of days, but the tomato plant looks like it needs more of something (probably nitrogen).

I didn't see the fish today and they didn't eat their food (fed them this morning). They were all hiding in the big PVC pipe at the bottom of the pond, but they look healthy enough. I find it a bit strange that they don't eat their food, because I didn't feed them a lot..

Too cold? or lots of algae on the walls, forgot what fish you have...

It's not much colder than it was when they still ate a lot.. And I don't seem to have any algue at all (the water is crystal clear). Maybe they just don't like being fed in the morning, because they did eat their food yesterday evening.

I bought 5 more fish today. They're goldfish/shubunkin/sarassa and they're all around 17cm long (the ide/orfe must be about 12cm). They're not as shy as the smaller guys I already had and they're pretty social.

Fish: http://nl.youtube.com/watch?v=iM8ryrJH59g

















Yay

Very cool, love the colorful new fish!

My goldies wont eat in the morning either, they are more afternoon fish

Nice looking water.

Wow, that water is clear!

What do those green & clear cones do?

I think it stops the aliens from getting the lettuce seedlings

Thanks guys!

The cones act as a small greenhouse (if you stick your finger in, it's really hot!) and the green ones also protect the small plants from bright sunlight. They also keep the snails, birds and most of the bugs out.


Actually, the aliens are not getting my lettuce seedlings, but something's been stealing the beans and peas I sowed. They found a couple on the surface and then dug up the rest (I think it's birds though, not aliens)... I'll resow them and put some cones over them.

Went to the beach today and got ~10kgs of shells. I'll wash them soon, and I'll add some if the pH gets below 6,5 again.

The lower leaves of my tomato are clearly showing a nutrient deficiency. I think it's a phosphorus deficiency, but it might as well be an everything-deficiency because there's not much nutrients going into the system yet (not a lot of fish, not a lot of fish food either)..


What should I do to keep the tomato from dying? The other plants look fine, though they're not growing very fast. Should I get some phosphate fertiliser?

I'm planning on getting an old blender and a meat mincer so I can make my own fish food.

Seasol, seaweed extract, fish extract - dont know about fertilizers

tom, crush the shells a little and either put them in the FLOW of water or bury them within the flood and drain depth of your grow bed.

This weekend four of the goldfish began chasing the fifth one - turns out we had one female and four males.. The poor girl was being chased around all the time for days on end! So we bought 5 more goldfish, probably all female; the older female gets a little more rest now, because the older males are also chasing a new female.
We also bought a sunfish and a baby koi. The sunfish is a good hunter, quite hard to spot (the autofocus didn't work on him either) and when we got a bunch of really small fish from a ditch the sunfish ate them all in no time.


Also a small video of the fish: http://www.youtube.com/watch?v=XJJ-nO9tJfE .

Yesterday though the female that was being chased around so much was all fluffy - I think the other fish may have damaged her slimy skin so it could be some sort of fish fungus. I put her in a big bucket and added 3g/l salt and a lot of air, hopefully she'll recover.



Anyways, the plants are mostly in a better shape.

Half of the cabbages and lettuces under the cones died from the heat though, I guess it was too hot inside the cones so I removed them. The ones that survived seem recovering.


The onions are growing very fast, but I think that's just the leaves. The spring onions all came up, and also a couple of radishes.



The tomato is still showing what I think is a phosphorus deficiency, but it's growing quite fast and it even has a couple of small tomatoes already. The monarda plant is doing fine, it's just as big as the one in the soil (but a little less green).


We also had a couple of AP strawberries already - they're perfectly sweet (and don't taste of fish poo )


We still don't have enough fish to supply the nutrients for the plants, and the pH is still too low so I guess we'll have to do with only a few plants while the fish get bigger, and add some of the shells I got at the beach (and wash them first) like Steve suggested.

Be careful about adding wild fish to your system, just in case parasites or disease are added aswell - mostly a problem if you get any other fish except for goldies

Looks great, needs more fish