Backyard Aquaponics
A place to discuss aquaponics

Personally I think pushing it is like saying the world financial crisis is a hiccup.

What crisis? ..... My wages have remained the same ,,my bills similiar ,,,petrol cheaper,,, and the Aussie economy grew last quarter.
Stock market back over 4,000,,,
It's largely HOT wind.
I just hope the BILL for the problems lands in the laps of the ones who created it.

For me and you Chappo, But nearly 10% of the homes in California are in default. No Doubt I'm actually better off. Half my fuel bill for 2 cars lower interest rates, even and lots of things much cheaper to take advantage of like vehicles with tax incentives on top of lower prices in years. Even hybrids which I'm looking at now cause I'm watching the price of fuel climb back every day. Knowing Refineries are investing for a reason. Building materials also (housing market down) much cheaper. The Utilities and food still about the same or higher. But no doubt the world is in a serious crunch.

That's OK guys... when the world un-crunchs itself... it will not be flat again...

I figure that if i leave a minimum of 600l in the tank, then i can have approx. 500l that can go into grow beds. So if the grow beds are 40% water then i can have bout 1250l of gb, which is about 4 bath tubs and a half barrel. I want to try and fit 5 bath tubs, 6 half barrels and a full barrel. Which would come to 2300l of gb space and 920l of water in all my gb's if all flooded at the same time (that's the dream anyway, but lookin at the maths i either have to split it into 3 seperate systems, decrease my gb's or expand my tank volume by adding 1 or 2 full barrels to it).
I'm gonna split this system in 2 and have 2 pumps running the gb's sequencially, as in pump 1 on for 15mins, then off for 45, pump 2 comes on 15mins after pump 1 for 15mins then off for 45mins.
So basically there will be a pump running for 15mins every 15mins.
Does that make sense?

Hi Jono

Multiple pumps and sequential flooding sounds like a good solution.

Have you considered using a sump. Can't see that mentioned anywhere in the banter.

Key difference there FF is 24/7

You have 75% more water filtration time.

The rule of thumb for stocking has usually been 3 kg of fish per 100 l of flood and drain gravel filled grow bed. Of course you also need enough water for them to survive in and enough flow and aeration for them to survive also. You might be technically within the rule of thumb with 36 fish that might get as big as 1 kg each but you will be pushing it if you are not experienced as a fish keeper with extra aeration, pumping and filtration on hand to deal with issues as they come up. Very heavily stocked systems can run into problems very very fast.

Do remember that a new system should probably not be asked to handle max stocking density in it's first season.

I sort of ran a little max stocking experiment earlier this week. Granted the fish tank I hooked up with was a little bigger than the bare minimum for the number of fish, I based the numbers on the grow beds. I put 60 adult tilapia into a 299 gallon tank and the total volume of the grow beds for this system is 250 gallons. Those beds flood and drain together by FLOUT and the pump manages to flood the beds about every 30-40 minutes. Slightly under size pump for the system. I think I'm getting enough filtration there but the pump doesn't provide enough extra flow to send some of the water back to spray into the fish tank. The Tilapia were at the surface gasping for air the next morning and tilapia are supposed to handle low aeration levels better than most fish.) I have since added an extra bit of pumping just for aeration (power head with venturi) and the fish were not at the surface this morning.

So, it is probably best to listen to the people closest to you that are raising similar fish to what you plan and start with the stocking numbers they recommend. As you gain experience, you will be far better able to judge how far you can push your system.

I now firmly believe that a simple system that does not have the system pump constantly splashing into it, definitely needs an extra form of aeration added and running constantly (air pump with stones or other diffusers or another pump to give some constant splashing and circulation of water.) Or better yet!!!!! Set the system up CHIFT PIST and either run the pump constantly delivering clean filtered water to the fish tank at all times for good aeration or running the timed pump you could then have an air pump or other small pump for constant aeration.

That worked well for me! I was only able to keep about 50 150 gram - 250 gram fish in one of my 300 gallon tanks. Now after adding a continuous bio filter, swirl filter, and running 24/7 I can keep 130+ fish in the same tank.

Agreed OBO, no arguement here. That's is why I gave Jono an example of the 24/7 you mentioned in your very first post. Not dissagreeing just reiterating.



Cheers

Running 24/7 will help.... IF you have sufficent fitration capacity ....

ie.... "Now after adding a continuous bio filter, swirl filter, and running 24/7".....

The key words... "after adding a continuous bio filter, swirl filter".......

RAS aquaculture systems can stock at increased densities.... because they have sufficient filtration capacity... that they run 24/7... they have enough filtration capacity.... to process the load

If you don't have enough capcity to process the nutrient load... running 24/7 wont help you...

Well it might help you a bit.... but not in the long term....

If you look at most of the early member systems... that successfully produced batchs of grown out fish... and look at the pictures of their water quality, and comments about getting to a point where they virtually didn't test water parameters at all....

It's because... they designed their systems with the 2:1 ratio....and stocked at 3kg/100L... from the start...

Most systems now... whether by constraint of budget, or availability of space and/or materials... barely start with a 1:1 ratio... and often double the suggested stocking density... and usually don't progress past the 1:1 ratio

And the frequency of water quality problems .... and fish kills ... has risen correspondingly IMO...

Yes there are members that have successfully grown out fish stock at higher densities and/or lower filtration capacities... and methods may have improved that viability....

But IMO... we have developed a dangerous trend to suggest that 1:1 growbed:tank volume is sufficient....

We forget that we are working with the actual overall volume of the growbed... and after taking into account the media volume... that we may actuall only have 40-50% as actual filtration volume....

With a 2:1 ratio... and allowing for the actual media/filtration volume.... the reality is then that the real filtration volume is roughly equivalent to the tank volume...

A minimum IMO.....

Ok, so i think that i've solved my problem.
I'm going to plumb in 2 extra 200l barrels to my main tank, these won't be used for anything but basically expanding the fish tank volume by 400l.
I'm going to be running 2 pumps to slpit the water, ie sequencial flow, and one of those would have a tee piece to facilitate airation and movement of water.
So essentially there would be between 25-30kg's of fish in approx 1000l at its lowest point, with approx 2300l of gb's.
Now the 2300l of gb's is going to be in the next 6 to 8 months and not straight away, but am pre-empting the water shortage problem early so i don't have to either pull my system apart to i can rectify the situation or start another system.
I may not even expand to that big, who knows.

thanks.
Jono

Now that sounds like a plan Jono...

Thanks Rup.

So i've done all my calcs right and everything? No doubt when i get more experienced i'll find that i may need extra airation and the such, but as long as i have the water (or lack there of) sorted out then thats good