Backyard Aquaponics
A place to discuss aquaponics

Good thinking Steve... I would have to agree.

The solids will eventually start to build up in that one spot under the inlet.

What would be the different to that and a RSG filter they just look like a heap of junk in one part of a grow bed

Sand, activated charcoal, and anoxic conditions by limiting the drain rate of the sand.

Update: had 1 goldfish for one week tomorrow. ammonia at 0.5ppm (have been over feeding it)

Have not tried to even out solids distribution yet.

System has stopped twice when the water level got too low. The double auto siphon system only worked well with the right volume of water and it is hard to tell how much is gone with all the levels going up and down so have added "prototype auto water adder" as shown in pic. ( a vertical pipe runs from the sealed drum of water down to the minimum water level))

I'm finding the irregular noise of the float switch pump disturbs the peace so am planning to get a slower pump that will run full time. (fast drain by bell siphon into growbeds and slow return to fishtank by pump.)

Not sure of the theory behinf putting the reserve tank to the GB instead of the sump/fish tank?

In my system (and others), the water in the GB drain to a minimum level and don't go below that - the water in the fish/sump tank takes all the fluctuations due to evaporations etc...so wouldn't it be more logical to have it flowing into the fish/sump tank when the level drops in there?

How big is the drum?...I add 20-30litre of water/day, so to be useful to myself, the reserve tank would need to hold a week's load of water...with smaller sized GBs this amount of water would be less, but I do see a drum the size in the picture only holding a couple of days supply...keep us informed how it goes tho as these are only my thoughts on using one

In my setup, the sump is separate to the fish tank. (sump bottom , GB middle, fish tank top)

Water level in sump determined by float switch inbuilt into pump (range 6cm) Water level in fish tank set by auto siphon air tube
When the GBs stop draining into the sump the pump wont kick in to fill the fish tank to start the auto siphon so I put the reserve tank there.
Its a 10L drum and youre right its pretty useless.

Anyhow, after reading over this forum and from my own experiments ive decided to swap the 300W float switch pump for a low wattage/ flow pump to get a slow pump up / fast auto siphon down system.
Advantages are less water flow back up problems, less pump wear from start/stop operation, cheaper pump, constant white noise and sump buffers water loss as you said. Also will turn my ugly sump into a productive duckweed and marron pond.

I actually bought the pump to recycle grey water with but got distracted by aquaponics while researching it!

...I was trying to be subtle

Update

Had 1 goldfish in system for 5 weeks now. Ammonia peaked at 0.5ppm after 1 week and dissapeared 2 days later and have not seen any since.

0.25ppm of nitrite appeared 3 weeks after I got the fish and I still have 0.25ppm of nitrite now, 2 weeks later. Ive got 3ppt (3g/L) of salt in the water. Did someone here say they had a table of how much salt protects against how much nitrite? I think earthbound mentioned it in a post.

Nitrate is at 10ppm and there is quite a bit of algal growth. I have been putting in about 10ppm of nitrate as potassium nitrate each week to keep the plants going until I get some silver perch. (I hear SP will be available soon!)

Its strange that the tomato does so well yet rocket wont grow at all. (yellow between the veins and yellow all over) I added 2tsp iron EDTA and 1 tsp manganese sulphate 2 weeks ago after the rocket had sprouted. The rocket is the tiny plants in the far bed.

I think my main problem is pH. The system pH stays at 8.1, I adjust it to 7.5 with about 5g of phosphoric acid 85%, and it goes back up by itself to 8.1 within a couple of days.
Has anyone else had this happen using pea gravel?
My tap water pH is 7.4 straight out of the tap and the whole system is just plastic and pea gravel.
I think Monya advised against jerking th pH around in another thread. Is jumping between 7.5 and 8.1 likely to kill the fish when I get them?

Tony from WA was having a very similar problem Brett.... but he was using bore/well water which in the end seemed to be saturated with carbon dioxide (I think)... was naturally carbonating and buffering the water....

Maybe try leaving any top up water in sunlight for a day or two to offgass any CO2 before using it and see if it makes a diference.

Either that or perhaps your "pea" gravel is "limestone" granite??

Jerking the pH around won't kill the fish immediately, but it causes them stress which will make them more susceptible to disease. As the system matures, the pH will naturally drift down, but that will take 6 months or so. Even if it is a bit high, I feel it is better to leave pH alone rather than jerk it around once you have fish in the system.

To expand on Rupe's experiment, test the pH straight out of the tap, and then after aging in a bucket for a few days. Then add some gravel to the bucket and test a few days later. Seeing when and where your pH is moving would be helpful. I believe it was dissolved CO2 that was affecting Tony's pH, so perhaps you have a similar situation.

OK, will do as suggested

BTW, I believe that the CO2 was causing a low pH of 6.5 in my bore water. when the CO2 off-gassed, the pH went to >8.8.

Despite doing a 90% water change I had >8.8 after 3 days. I think that is due to li,me deposits from the water forming on the HDPE pond and in the iris pots in the FP.
I did a 75% water change (unintended) I used lemons to drop the pH.

I measured the pH at 8.0 this afternoon.

I will check pH again tomorrow

Got 102 silver perch and 9 marron from Gidge on saturday. Finally, woohoo!

No losses yet as far as I can tell and I do recommend this supplier.

Still havent got around to testing whether tap water pH goes up after standing. The problem actually went away during the 10 days preceding saturday; pH dropped from around 8 to around 7.4-7.6 (7.55 today) and during the same time the 0.25ppm NO2 which had been recorded over 16 days dropped to 0. I believe the NO2 to NO3 conversion kicking in likely caused the pH change but will still do the tap water test soon.

Atta boy Brett... get any pictures of the fish and Marron?

tthdghgh