Backyard Aquaponics
A place to discuss aquaponics

Transferred the older aerator to sys 3 as well as changed the wiring around so it's all under the tubs. I'll need to make a splash guard so water doesn't get sprayed on.
I think I'll put Seasol into sys 2 next time as the sys 3 chems are about to plumet.

I hope you have that on a circuit protected by an RCD type circuit breaker!

+1 on that for certain.

Yes.

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I managed to prove the third system is far from idiot proof.
The dispersion pipes can rotate on the central vertical delivery pipe from the pump and I think a possum had climbed or jumped onto the netting and moved one of the tubes too close to the edge where it dispensed about 200 lt over the edge onto the ground. Being a low Ph system I could only put the 100 lt I had in reserve in as top up.
The system is still cycling and the water test showed no big change in the chemistry. I'll go and get some more low Ph 6.2 water shortly for top up and reserve again.

Looks like you're cycled Pete and have been for a couple of weeks from the tests . No ammonia, no nitrites, 40 - 80 ppm nitrates --- You're good to go except for one thing - your pH is too low. It's reading 6.0 and the minimum the test can read is 6.0 so it could be lower. Bring that pH up or you risk having the biofilter crash. Get er done and get on with the growing

Will loading with fish raise the ph?

No, it will cause it to drop even faster! You'll need to bring it up to somewhere in the pH6-7 range before you add any fish, and maintain it there.

I'm currently adding 80-100g of Potassium hydroxide (KOH) per day to maintain my pH in the low 6's range (you wont need anywhere near that much).

Some useful compounds are: KOH, Ca(OH)2, K2CO3, KHCO3, dolomite, CaCO3 etc

Last night I added 100 lt of town water which has a ph of 7.4, thinking about it later maybe I should have topped it up with Sy 2 8.2 water.Anyway the reading is definitly yellow 6.0 now.
While trying to understand the ph behaviour I tested some washed scoria fines left over from Sy2 that had been left out in the rain looks to be about 8.0.

You might want to take a known amount of system water and figure out how much it takes of whatever chemical you're using to get the pH you want. You can adjust the system pH up to where you want it by using that information because the amount for the whole system will be in proportion with this. Hope that makes sense to you. When you have fish the pH change should be done gradually (0.4 pH units at a time) but without the fish you probably can bring the whole system up into the 6-7 range in one go.

My intention is to raise the Ph in the (conversion) sy3 over 2-3 weeks to 8.0 while the fingerlings are in there. Since sy2 (receiving) 8.2 doesn't have chemicals controlling its ph I am reluctant to use them in sy3. I was planning on doing water changes from sy2 at say 18 lt/day to elevate the ph until the two systems are about equal.
Do you see any issues with this?

I don't see a problem with that although I'm not sure it will work for very long. Nitrification will push the pH down eventually.

This morning I extracted about 80 Lt from Sy3 and refilled with 72 Lt of Sy1 & 2 water. This evening I tested the ph at 6.5. I'll check in the morning and monitor how quickly it drops. I had hoped to get some fish this weekend however the weather and the ph issues stuffed that up.

The morning test was 6.5, we had a lot of rain overnight so I put the spare poly carbonate sheet over the frame of sy3.
I collected 40 RB trout 3-5" fingerlings this afternoon. A test of their water in the bag revealed a Ph of less than 6.0.
The fish seem happy enough in their new tank splashing water occasionally so I clamped some dark green shade cloth over the tank.

Since I got the fish 4 days ago I lost 29 of them . The water seemed fine although the ammonia was up which was expected, the ph bounced around between less than 6 and 6.6. I mixed 5 grams of calcium carbonate into 9 lt 8.2 ph sy2 water every couple of days and dosed with 8.2 twice a day. I hadn't fed them for the first three days. The last 36 hrs have seen no fatalities. A lot of head banging went on starting a few hours after I got them. It seems as though when they get spooked they race off and bang into the wall of the tank because they're used to a pond 6 x 15 m in size.
Once I get these survivors into ft2 I'll install curtain/cushion around the walls to eliminate the kamikaze effect for the next batch.
I put a stainless woven wire mesh over the outlet of the tank and changed the cycle time to 15/45, and was amazed at how clean the bottom of the tank became after the intro of the fish. Anything that lies on the tapered floor makes its way down to the outlet.