Backyard Aquaponics
A place to discuss aquaponics

Simso, what type of timer are you using to achieve 4 minutes on 56 minutes off? Also, how long does it take for your GB's to drain?

These,

Got them on ebay, the first timer runs my pool pump, bit of a waste for a good timer, the second one turns pump 1 on for 4 minutes in tank 1 and then the following hour it turns on pump 2 for 4 minutes in the other tank so that way I have even pumping out of each tank, and the tanks have a large 3 inch cross tube connecting them for even tank levels

Agreed regarding pumping capacity Simso, you have smaller tank and a similar large pump we are using on a 5000 litre tank.

The general consensus seems to be to aim for complete turn over at least once an hour. If you can do that in 4 minutes and your timer allows for the small increments go for it. If 4 minuted fills you beds to overflowing the standpipe but does not turn your water over completely (from your previous post it seems you are turning over a little less than half) then maybe consider 5 min on 30 min off so you are turning over the whole 2000 litres.

PS Your tanks look nice and clear, do you have an overview picture of your whole system, I could not find your system thread (if you have one).

Nope dont have a thread yet, maybe soon.

Thats exactly what Im trying to work out at the moment regarding how long the pumps really need to be run, I would if it came to it, reduce the off time and then say cycle 4 on 25 off rather than 15 on 45 off

Had lots of troubles regarding algae and then I covered the tanks and had issues with barra stressing everytime I lifted the corners etc, when I finally made the greenhouse and put some laundry baskets in the tanks for them to go into when they want to hide, its been smooth sailing since, the fish you can see easily from the outside without even slightly upsetting them. quick photo of my semi type greenhouse

Great looking FT greenhouse. I plan on doing something similar with my home tank eventually, at the moment it has a 1/2 hour structure over it to stop the tea tree leaves from getting into it and reduce light.

School tank has no shelter structure but I am hoping to be able to get a patio structure over it next year if budgets permit and I can find somone who wants to give the school a good deal. No structure makes controlling algae a pain, we are currently experiencing our second bloom for the year, first one happened at the beginning of spring when water temps first increased to above 12 degrees.

I've seen those timers on Ebay. But thought they had a limited amount of on/off switching per day. Are you getting 24 on/offs in a day with them?

Yeh they have a limited amount of on/offs 15 to be exact, so you can turn it on and off 15 times and select which power point in that period, for me that covers 7am to 9pm no problems just like I had it for hydroponics,

I bought the second timer unit becuase I was going to only run one pump of each timer unit and then I would have up to 30 individual on/offs but I found the single timer unit one was more than sufficient for my needs

Burnsy, yeh Im pretty happy with how well the fish enclosure came up, dont know how well it will work with algae on really hot days as only the roof and front door entrance are shade cloth, the rest is simply the plastic lattice, but if I find I start getting algae again I will simply put some shade cloth on the back of the lattice or that clear UV reduction plastic sheeting, depends if algae grows from UV light or simply light

You'll only get algae for the first year or so Simso, so dont stress

Nah not stressed at all, massive learning curve especially with the barras. The silver perch were like a set and forget they look after themselves, but barra talk about timid animals and easily stressed.

For info the first two weeks I had them they had massive stress lines and then a few had lost them after about 2 weeks, after getting sick of the feeding issues ""not feeding"", I decided stuff the current setup with tarps and shadecloths on the tank and food getting trapped and stuck on the tarps and simply built the enclosure,whilst building the enclosure most of the barras went white and scaley with a 1cm wide white stress line, after two days in the enclosure not a single barra had a stress line on it. Go figure.

PS sorry burnsy but it appears Ive kind of taken over your post and topic and taken it down another path, apologies

Burnesy, I have no issue with overflow either for all of the reason given; to a point. However as you said overflow is not as effective for ammonia conversion. If it was I could have large amounts of fish and as long as I pumped the entire fish tank through a small filter every hour (overflow and all) then the system would work, we all know there is a limit. Having said that, from my own experience water quality is good over a massive range of pumping regimes.

I thought it might be useful to mention that pumping 15 on 45 off works best when a system is closer to a 2:1 ratio and the pump is appropriately rated to move approximately the right amount of water (slightly above tank capacity) in the recommened 15 minutes. This is a very efficient way to do things if 15 on 45 is someones ultimate aim. A larger pump is less efficient as it generally uses more electricity and fills the grow beds too fast (overflow again). A smaller pump can also have a problem if it can't keep up with the normal outflow of the standpipes.

I have run into all of these issues, as have others (lots of mentions in this forum), none of them are deal breakers as you say and are easily fixed.

Good post FF

All great points FF and I don't dispute any, just looking for the most effective pumping regime for the school system that is a six bed system running from a lightly stocked 5000 litre tank that is fitted with an ebara pump capable of filling the beds in less than 10 minutes but by the end of a 15 minute cycle has only turned over around half the FT.

It looks like in our case we should be possibly straying from the proven 15/45 and seeing how the system goes with 15/30. This thread has brought up some great discussion, it is always good to hear what otheres are doing and what has and has not worked for them.

Burnsey,

How did you go in the end - did you change the pumping cycle to increase turnover and how is it working?

Very interested because I have a magnified version of same problem, running 20,000 litres on 2 x 500ltr BYAP growbeds, currently 15/45 pumping but obviously turning over a fraction of the water an hour (but lightly stocked with 31 Koi).

I had a second algae bloom a couple of weeks ago (seems to be clearing now), following one a few months ago when I got started.

TCL earlier said:

"And the limits of the grow beds are a big issue for those I know are running something of a swimming pool with only a small amount of grow beds. Those systems usually need some additional alternate filtering to keep the water nice.

I do think adequate water turn over is a big step to improving water quality if problems are apparent."

This fits me exactly, and currently I am running a secoond pump with a small jap mat filter which I would really like to turn off but haven't done so yet for fear of water quality issues. Am thinking that if I turn this off and increase to say a 30/45 cycle I should be OK... thoughts?

For your situation, why not simply get an ibc ($50) hide it somewhere or bury it and fill it to the top with gravel and use it as a plain bio filter, I think that would solve all your problems

Mike, I am yet to make any changes but will change to 15/30. I don't expect it to stop the algae but it should improve general clarity.

The algae is triggered by water temp changes, not just nutrient load but it is nice to hear OBO say that they stop occuring after a few seasons.