Backyard Aquaponics
A place to discuss aquaponics

so, i've setup pretty much as suggested. FTs high SOL'ing into a temporary holding tank between the FTs and GBs. planning to take care of the solids here before getting into the GBs.

now weighing up flood and drain vs. continuous flow - i have heard it also described as 'continuous drain' which to me seems like it would be referred as that if the height in the GBs was variable based on the pump output? anyways, it seems simpler than flood and drain in my setup but there seems to be issues with getting the GB wet enough in all places without irrigation grids. i'd have though the 'grids' would be best buried in the gravel to keep the top of the GBs dry and the water out of the light as suggested in many other posts but this seems very cumbersome to build and maintain.

i really don't want another pump running for the GBs to do flood and drain and don't like the idea of auto-siphons either. anyone have any other cool method of ensuring the GBs get an even water flow? I was also planning to turn the pump off once a day for an hour or so and let the GBs totally dry out to avoid root rot, etc..

@buckettea - If you are going to go CF (constant flood / continuous flow/ continuous drain) you can take a look at my system, from how it has been performing, i don't see too much of a problem with only one point of entry into my GBs. The only thing is that i do have some algae where the water enters the GBs. It is actually not too bad, did not affect the water quality at all.

It comes down to your own preference i guess, some put up with the algae while others will have a flexible hose that they move around buried to stop the roots tracing back into the pipes. Which will happen if you bury your inlet permanently.

you can consider timed flood and drain. Please read the attached link for a better idea. Another link you should take a look is the trails done by BYAP.

http://backyardaquaponics.com/forum/vie ... +and+drain
viewtopic.php?f=51&t=8621&hilit=trial*

Regards

thanks curious, i'll check it out.

one question, at what level in your GB (percentage) do you feed the water in/out? i read continuous flow should have the water going through in the lower part, but i don't know if that's about a 1/3 (or other) and if it depends on the depth of the GB.

my GB's are likely 1/2 IBC, so 500L, and i'm planning to use scoria as a medium. i don't want to drill holes in the sides of the GB only to find they're too high or too low.

scrap that, i see you're dropping the water in from the top and controlling depth via the standpipe. i'll do the same for now (i was hoping not to have to even make standpipes, but i guess i need a fail safe in case the water's coming in faster than it's coming out!)

@buckettea - I think it i s better if you have the stand pipes, allow you more flexibility for modifications. For example drop a bell on top and you get a siphon, or drill a small hole at the bottom of the stand pipe and add a timer, you get a timed ebb and flow.

Regards

+1
Make sure you put in a big enough gravel guard/shroud to enable you to get your hand down to the bottom (eg. 90-100mm) and so you can fit a bell over the standpipe if you end up wanting to turn it into a siphon. The gravel guard needs more holes than plastic to allow sufficient flow - its not something that you can go back and fix easily once the gravel is in the GB.

I have a 32mm bulkhead fitting with a 32mm standpipe for both my GBs. The gravel guard is 100mm and the bell is 60-70mm (can't remember & its too dark and cold to go out and measure it now). For my constant flood half barrel GB I have holes in the bottom third of the gravel guard ensuring that the water is pulled from near the bottom of the GB before exiting the standpipe. When putting in the bulkhead fitting I cut a hole with a hole saw in the endcap which fits my gravel guard and fixed it to the bottom of the GB between the rubber seal and the bulkhead nut. The gravel guard then sits in the endcap holding it in place. I was unwitting enough to use small screws to fix the gravel guard into the endcap so I couldn't accidently pull it out, but now realise it stops me from turning it to break off invading roots . Just make sure your bulkhead fitting is nice and firm and not leaking before filling the GB with gravel. And it would help to have the underneath accessible in case you need to work on it or deal with leaks.

You don't want to glue in your standpipe as you may want to remove it to shorten or lengthen it or add a drain hole down the track. I have a socket fitting screwed into the bulkhead for the standpipe to sit in, but they can get stuck with all the biofilm even if they are not glued, so I found when trying to remove one a while ago.

There are plenty of constant flood and DWC systems where the roots are permanently submerged. There have also been comparisons done of constant flood verse flood and drain - both seem to work well with different folks having their own preferences based on their individual systems and experiences.

I hope that is of some help and not confusing the issue. Keep it simple with your first system, and enjoy the journey

+1
Here is the link to what joc is refering to.
viewtopic.php?f=51&t=8621&hilit=trial*

As well as how to build a timed ebb and flow.
http://backyardaquaponics.com/forum/vie ... +and+drain

Regards

>>I hope that is of some help and not confusing the issue

thanks, but I don't need anymore help to get confused appreciate all the advice...

will def. go with standpipes and possibly add bell siphons later.

i did read a thread about going through the side with an elbow/upright instead of the bottom which is tempting given the IBC can then sit directly on the ground. someone chimed in saying the height of the standpipe needs to be 24" above the horizontal - any rules of thumbs around this? I have a _reasonable_ drop from FT to GB and GB to ST, but I don't think 2ft per step... after my first experiment at running the pump i'm a little concerned about water flow:

i setup the ST, and pumped into a holding tank (IBC with tap fully open) and then let it drain back to the ST (davey pool pump XB260, nowhere to be found are the specs.) and found the ST emptied at ~500L in 2-3min and much faster than the gravity feed back so this is problem #1. i can just buy a different pump of course, this is one i had lying around... atm one option is to tap off it at the ST and drop some of flow back into the ST and perhaps get some benefit from extra aeration into the STbut it seems like a waste of electricity. another option is to put a tap straight after the pump in line and restrict the flow but i doubt this is good for the pump. i'm hoping that as I add FTs i'll effectively reduce the input to each tank and that might solve it without any intervention but given the effort going into cleaning the IBCs I have I was hoping to not rely on this is as the solution (besides the fact that I might want to run a single tank at sometimes). the last option is to put the pump on a timer, but i've heard they're more prone to failure if on/off'ing too often and then of course another point of failure in the system if the timer fails.

i've ordered 1.5" uniseals for the GBs which i think means 50mm pipe (hoping i've ordered the right thing and the pipe is readily available?) so hoping that will be sufficient given I'm planning on 25mm inputs to the GBs, each with a tap.

i decided after getting advice on another forum to put in radial flow filters after the FT, and have the same concerns there regarding drainage rates, currently planning on a dedicated filter per FT just to be sure. i found a design where the bottom outlet of the IBC FT is fed into the bottom of the filter barrel removing the need for SLO'ing, sounds fine provided the filter plumbing doesn't fail - how good are these uniseals? the concern being that if it failed the FT would empty out. i've not found a supplier of bulkheads yet, any suggestions?

You could try the B store http://www.bunnings.com.au/garden-rain- ... 5_p3113886, my local irrigation store also had them. You can get female/female, male/female and male/male tank outlets (bulkhead fittings) in different diameters depends what suits and what is available. I had to revise how all my plumbing fitted together while at the store because I couldn't find what I planned on. Pays to have a good diagram with you, or find an online supplier with the range of fittings you need and put in a big order.

Be careful not to mix up pressure pipe and fittings with DWV pipe and fittings as they don't fit each other - or you have to get 'creative' to make it all work.

50mm is 2". From memory your GB inflows will be gravity fed from the FT and filter, so it would pay to have them much larger diameter than the pressurized inflow from the pump to the FT. You could have a larger main pipe from your FT/Filter with smaller outlets to each GB. A little bit of water will gravity flow through a large pipe, but you can't get a lot of water to flow through a small pipe under gravity unless you have a lot of head height pushing it out. I have found that it pays to build in a number of bypasses so that you can take different parts of your system off line without having to shut down the pump and to deal with excess flow.

Yikes! that is 10,000+ L/hour, which is rather a lot even for a couple of IBC fish tanks. It would also make your ST a washing machine if you short circuited the excess flow back to the ST. You could always keep it as a back up.

thanks for the link, i'd have called that a 'tank flange'. funny enough i picked up a handful while at that place on saturday when i saw the price, but then didn't take them as while the price was as advertised on that webpage they were more like $12 at the register (i was getting them for $11 locally). i might go back now

i thought the idea of 'bulkhead' was that the pipe fit snug and there is no threading so no additional fittings and it's adjustable? what am i missing?

yeah, i thought yikes too with the pump! it's only small (i have a couple of others that are twice the size) so was surprised. i've lifted the FT a little higher which might slow it down with head height (~3m) - one question regarding the feed into the FT: do you just drop your water in the top or it's somewhere else in the water column? i thought that from the top would provide some aeration but not sure about the noise bothering the fish much? one utube i watched with a 'venturi' of some sort providing the aeration was promoted as it was low noise. i'm trying to avoid drilling too many holes into things that hold water and hoping to just drop it in the top.

A uniseal fits into the hole you cut with a rubber lip either side of the hole and the pipe is pushed through it. Colum has a great youtube clip of his struggles and technique of getting the pipe through the uniseal, and there are a lot of discussion treads about how to get pipes through uniseals. A bulkhead fitting has the threaded shaft that freely fits through the hole, with rubber flanges and nuts that screw up tight (one end might be fixed). Well, that is my understanding, and I don't even know why they are called what they are called- maybe terminology from another part of the world? . The bigger the diameter, the more expensive they are, but make sure you get the size you need, not the size you think you can get away with . Then you just need to get the PVC fittings to screw on or into the bulkhead fitting. Many use uniseals because they are cheaper.
I think Stuart Chignill had a fish tank design thread viewtopic.php?f=8&t=22254 that talks about trying to set up a circular flow in the FT with a manifold with angled outlets down into the water (sorry, a poor description). As the fish stir up the solids they are gently swirled towards the centre where they are remove via the SLO. Of course it is harder to set up a circular current in a square tank.

>>set up a circular flow

i was thinking this at some point, but not for that reason. where i grew up there were many trout hatchery's and they were simply diverted water from a running creek. the nice thing is that it exercises the fish and they grow faster.

btw - (now that i've read through it) that thread is way beyond me at this point

Me too! I put together a water distribution manifold with lots of drilled hole to gently shower water into the FT - seemed like a good idea at the time . But the water backs up over it because my SLO is too small and I have no spare head height to relocate it. I have since read that aeraton is more a function of surface movement, so I reckon it would be enough to have the inlet as a angled pipe that encourages a swirl in the tank. You can always add to it or redesign it from there if need be. If you have it under the the surface be careful it doesn't siphon when the pump is off.

Gunagulla has recently posted pics of his water circulation set up on a big round FT.

i like the angle approach for now, too much to do... and for sure on siphoning the FT...

re your SLO, i'm sure you've seen the vid of the RFF where it takes the solids out the bottom of the FT rather than the top. i did build a SLO, but planning the other method as well on another FT. seems more sensible, even considering the potential failure of the input to the RFF which i think can be overcome to a satisfactory degree. Not sure i understand why more people don't do it this way? I can see maybe you don't get the stuff on the top of the FT surface, but perhaps you can do both...

you'd at least get more throughput