Backyard Aquaponics
A place to discuss aquaponics

So back to some of Cyara's questions,
Grow beds acting as heat exchangers, no the growbeds don't create heat as OBO said, they heat up in the sun and will do a good job of heating water when it is hot and sunny. In winter, they will chill the water at night if not protected. The reason the gravel beds are so good at this is they draw air down into them as they drain which given the surface area of the media, allows the air to transfer heat or cool to the gravel. Then when the water fills up the grow bed again, it takes on some of the temperature of the gravel.

Water makes a wonderful thermal mass and the more of it you have, the slower the temperatures will change.

Small systems can work and you still can have fish in them but they also need more careful attention since as OBO said, if something goes wrong, you don't have as much time to correct it before it could be too late for the fish. If you can start a small system and fishless cycle it (good practice with test kits and learning about pH) Once cycled, you may still wish to put some small fish in it, just don't overstock and choose fish that will bear the temperature range.

I do kinda like the idea of the big water source at the top, perhaps instead of having your top tank be a flush tank, you could use it as a header tank that slowly trickles down. Some ways you might be able to effect "slow/fast" might be that the outlet from the bottom of the header tank might be a very slow drain. Then up nearer the top of the header tank would be an "overflow" drain that would be much faster and it would feed the system fast when the header tank is full and the pumps are running. Then if the wind or power dropped out, the tank level would fall a bit and the system would just feed from the slow drain in the bottom of the header tank. You might still want some sort of battery backup air for the fish tanks. Perhaps triggered by a float switch in the header tank. Now this idea has another big drawback, if the power is out for very long, you now need a sump that will not only hold all the water from your grow beds (plus the extra for the pump space, top up valve and evaporation leeway) but you now need to to be able to handle whatever amount of water is in the flush tank on top of that.

How hard is it to dig in your location? Perhaps instead of needing to build up the sides of the sump higher, you could gain the extra volume needed by digging?

And about the algae. Here is a thread with a link you might find interesting.
http://backyardaquaponics.com/forum/viewtopic.php?f=11&t=4060
It seems to explain a fair bit about algae though it probably also brings up many new questions.

Interesting. I will be using landfill around my ponds to rest the GBs on so could reap something from that. I like the idea of switch off at 8pm. Sun goes down and energy no longer required. No forced cooling of the water cos tilapia like it very warm. Time to get the batteries recharged overnight with wind power if using and windy. Thanks Steve.

If shutting things down overnight you may need some method of keeping the ponds aerated. Of course, if your system is under cover of greenhouses, this might not be such a concern.

I mean that the temperature issues over night might not be such a concern. You will have to experiment to see how much extra aeration you might need for the tilapia.

I like Steve's idea of switching off at night. Except perhaps if we have a scorcher and I need to bring temps down a bit. That would be unusual because tilapia grow best in hotter climates than here. I like the built in temp control factor of pumping at night if do need to cool down the system though. The plants need to be considered too.



I might do a little indoor system with buckets. I have mozzied around different shops to find a test kit like those I am reading about but not found one yet. Probably need a speciality store. Will keep looking or order off the net. I don't often go all the way into the suburbs.



Interesting. You have got me thinking. I like the idea of a flush valve in the top tank ...... but if I was in an emergency situation with the top tank not filling enough to trigger the flush valve then a slow drain could be effected from the bottom by just pulling out a plug. This could be a trickle feed.



I will be installing large landrover batteries as part of my power system. Practical experience will show me how many I will need.



Hmmm.... the trickle feed would have to be used only in a real emergency where plants are wilting. The sump will be big enough to handle all the GB water so shouldn't overflow.... ooops! ... just thought.... sump must be big enough to handle all GB water AND flush tank water! Mustn't it? Of course there is always the bicycle... ..... knew I would get fonder of that bicycle! Wonder if Jaymie ever found where to buy those bigger thumbs.... Might need a few of those to slow the flow while pedalling away...



I have been thinking of that. In some areas I am on bedrock but between can be quite large areas. It might be worth my while just to dig down and use these boulders as the basis of my sump. The shape is not really important and I could just close between and waterproof as normal. The sump might prove very expensive otherwise. Will let you know.

Good point. I think I would want to keep the aeration going. Just shut down the water flow.

Hi HGC. I have uploaded my design on the new thread.

The trickle flow and adjusting it could be as simple as a ball valve on the line. Trickiest part will be keeping that lower drain from getting clogged up so you will want to design it in such a fashion that you can clean it easily. Like a cleanout plug so you can poke it with a stick when needed.

If the beds are designed with FLOUTS instead of auto siphons, you should be able to handle either the fast flow or the trickle flow without trouble.

Yip. It was a dumb question. But I knew there was some info there I was missing .... so had to ask. (GBs in flood and drain cycling influence temps.)

At least I didn't blow my cover.... (newbie APer hides behind blonde hair to disguise brilliance as winkles out industry secrets.... .... yeah .... still safe. Lots more dumb questions lined up.) Thanks for your patience OBO.

Yes. Quite simple. Ease of maintenance. Will bear that in mind cos I like that idea of a second flow system.



OK. WIll make work of researching flouts. Thanks TCL

Your not dumb lol

If you want to know how much battery backup you need, just post your pump and battery specs, its easy to convert the battery AH to running hours.

I have 200AH of batteries, which gives me 40 hours of aeration running time independant of the main power supply, if the batteries are fully drained. Usually you only discharge the batteries by 50% at the most. I figured 20 hours was plenty, can always plug the car into it I suppose

For a battery backup system, it is probably worth while to look into deep cycle batteries rather than just depending on car batteries or something. Of course that all kinda depends on price/availability in your area but normal car batteries are no meant to be discharged much at all and their life quickly declines if you drain them down very far very often.

Now deep cycle batteries are designed to handle draining down to like 50% regularly and are far better at recovering from even deeper draining than the car batteries though it's best to avoid running any of these kind of batteries totally flat.

So anyway, before you go buying the land rover batteries (for all I know, land rovers might use special batteries and my recommendation here could be lame) do some research about batteries and alternative energy systems as well as deep cycle batteries, marine batteries, gel batteries, and AGM (absorbant glass mat) batteries. Keeping in mind that the bigger amp hour batteries and the gel or AGM batteries will require special chargers or charge controllers. But that will all be down the line after you get your first section of tank and grow beds online.

Thanks OBO. Will do. For sure.

I think I will do some research on the net about what is available here. Maybe someone in SA will see this post and make some suggestions. To me a battery... was a battery ...was a battery... Obviously not. Amazing all that is needed to get an AP system going. Is wonderful! Even the building I am learning will be so useful. Makes me flat-out exhausted some days! ... but is so amazing to see stuff take shape. My brick-laying is even getting straighter. Can't wait to use it on the AP system.



Sounds the way to go. I will rather save up to spend the extra than be sorry.



Yes. Wow. Glad to be starting smaller - but I must keep the end in mind all the time to guide me even in start up stages. So really great to know of all the options. Thanks.