Tank Ratio enhancement through carnivorous fish

[William J Silverthorn]

I'm trying to understand this concept thoroughly before designing my first Aquaponic system. I'm finding plenty of advice to say "stick to the recommended ratios" or else bad things will happen...

so if you have too many fish and not enough media space or growbed or biofilter to take care of the waste, then the fish poison themselves and die... I get that part and I dont intend to stress my fish out.

I'm wondering about the alternative deviation with too much growspace and not enough fish, would not harm the fish at all, but instead result in possibly slower growing conditions for the plants who dont have enough Nitrates to keep up with optimized growing speeds.

I was thinking of using a single IBC tote fishtank combined with 4 growbeds with autosiphons and a single continuous pump through a sequencing valve into those 4 growbeds. my first concern was the obvious straying from recommended 1 to 1 ratio, however I wonder if using higher protein feed with carnivorous breeds would provide an elevated output of more potent fertilizer that could fuel the needs of extra growbeds?

I have not found a great deal of warning in this area, since most immediate danger lies with the fish and not with the plants... so... has anyone experienced this first hand or should I experiment with it myself?

[TCLynx]

Keep in mind when you try to connect all grow beds together like that and have a single siphon, you need the pipes and fittings through the grow beds to be a lot bigger to make sure you are not restricting flow out of the grow beds since you want them to all flood and drain well and you don't want the siphon to suck all the water out of the drains faster than the water can flow out of the grow beds.

I would probably recommend that you do separate siphons in each bed, that way you can do affnan style siphons and not have to worry as much about getting the flow to siphon size perfectly balanced.  See feeding 4 separate beds but having just one siphon means it could be a little tricky to get the flow balanced for the siphon while making sure each bed gets good flow too.  But if you have one siphon per bed, that means you can have a valve feeding each bed and you adjust that valve to balance that one siphon.

Be sure to add an overflow so that the excess water that is going to the fish tank can get back to the sump in case your pump is not perfectly balanced with the siphon flow requirements.

If you go with the single mega siphon, definitely be sure to add overflows back to the sump directly from each grow bed in case something causes the siphon not to work or one bed drain gets a clog or something.  Actually overflows are a good idea in any case.

Now you are right that you have to be prepared for the contingency that all four bed siphons might trigger at the same time so the sump needs to be big enough to handle that, however, that may happen only rarely and there will be less water level fluctuation in the sump most of the time if you have separate siphon which will keep the pump in more water so it doesn't have to work as hard or isn't subject to overheating while the sump is at it's lowest water level.  (this is one of the problems with a very shallow but large footprint sump tank, if the low water level is barely above the pumps functional suction level, when the beds are almost flooded but if the pump starts sucking some air (because perhaps you didn't top up the sump tank lately) and there won't be as much flow so the flow to the beds slows down and the siphon only trickles over the top never kicking in so the pump continues to suck air (see the viscous circle coming?)  If you are sucking the sump tank down to almost this point every time with the mega siphon, this is going to be far more likely to happen.  If you are running separate siphons (especially if they are not all sharing the same drain line), this sort of thing will happen only rarely, like maybe the first time you fill the beds and then maybe if you pull stand pipes and drain all the beds with the pump off and then put all the stand pipes in and turn the pump on but only likely if you have the flows into each bed exactly the same and the media and plant root mass is exactly the same in all the beds.  And then on rare occasions the siphons might all align so all beds are flooded or drained at the same time but it will not be common.

Now if you are really hurting for space and you really don't like a big sump tank that doesn't do anything else...............

Well perhaps if you really like the mega siphon idea, I've played with the idea of doing a SUMP/grow bed.  Essentially you could have two regular grow beds hooked together with the combined siphon so they flood and drain together and then have two other grow beds set lower so the mega siphon can drain into them (make the sump/grow bed a bit bigger or perhaps deeper so you can create a spot to put the pump)  This way when the siphon beds are full the sump/bed has a low water level and then when the siphon beds drain the sump bed will flood.  This could be a bit tricky to keep everything all balanced right because you can't let the sump bed drain all the way because you pump needs to be in water but I've done something sort of like it before.  I've also done systems where the sump tank is also a raft bed.

[Jim Fisk]

I HIGHLY recommend making your sump LARGER and DEEPER than you think you need rather than just big enough or otherwise you will be constantly checking levels and adding make up water due to everything from small leaks to evaporation. A good size sump IS a very important part of your system and should not be short changed.

With 5 bell siphon beds (so far) I have a 275 ibc buried in the ground and only have to ck the level every few weeks or even once a month and it is a deep sump (4' deep). If you can bury your sump you add maximum flow potential and you want flow to be as quick as possible to keep things from building up in your pipes which can throw everything for a loop down the road from siphon failure to pump running dry . This design is asking for trouble in so many ways I will let TC spell them out as she already has so well.

William, have you Googled "Affnan Siphon" yet?

[William J Silverthorn]

Not yet. I'll google it.
I'm liking this 2 tier growbed idea.
I can have 3 growbeds together, and the sump parallel with a 4th growbed at a lower level, reducing the necessary water capacity by a large amount... not sure if 2 over 2 would be too difficult to juggle. this sounds like a fun idea to play with.

Jim Fisk said:

...William, have you Googled "Affnan Siphon" yet?

[TCLynx]

Perhaps this picture will give you some ideas

more diagrams are available at Useful diagrams

[William J Silverthorn]

I'm looking at the designs for Affnan siphon and I dont see the difference between Affnan and Bell siphons.
they both have a media guard.
they both have an outer creating a pressure barrier. (one calls it a bell, the other doesn't)
they both have a standpipe and a reducer that creates suction after the water spills into the standpipe.

they seem like the same idea to me.

thanks for the diagrams

[William J Silverthorn]

Ive been playing around with this idea of a sump parallel growbed, and there are a couple issues I cant get around.

the lower growbed(s) will fill at the speed the upper growbeds are draining, and...
the lower growbed(s) will drain at the speed the upper growbeds are filling.

so the quick drawdown of oxygen becomes a slow one, and the filling is quick rather than gradual.

as a result the lower growbed media is wet longer than the upper growbed...

also, the sump tank volume will need to be balanced just right so that right after the siphon drains, the lower growbed has the desired maximum water level... this could take some specific number of spacer-bricks in the sump tank to get the volume just right, but then I will need to keep checking the volume every so often because if a little too much water evaporates, the lower growbed will suffer. this diagram sort of illustrates my point.

I initially liked this idea because it would significantly decrease the necessary sump size, but it invites a complexity with the water levels. also having the growbeds at the same height makes them easier on the back during harvest and planting.

I'm thinking I should follow Jim Fisk's advice and go big with the sump instead. I'd like to go with the individual siphons but, how do you manage the water level at a glance? if I think my water level is too low, add some water, and then find out that my siphons were just about to fire all at once, overflowing my sump, I'm going to be wishing that I didn't add that water. with one siphon I can tell at each flush where the top water will be, which is nice, although carries a consistently large fluctuation in the sump water level.

Jim Fisk said:

I HIGHLY recommend making your sump LARGER and DEEPER than you think you need rather than just big enough or otherwise you will be constantly checking levels and adding make up water due to everything from small leaks to evaporation. A good size sump IS a very important part of your system and should not be short changed.

...

[Leo White Bear]

Get rid of the vertical pipe in the fish tank.  If power should go out, you will be siphioning all the water out of your fish tank,   It doesn't take long for this to happen.

[TCLynx]

William, the regular bell siphon doesn't have a reducer.

The affnan modification does.

William J Silverthorn said:

I'm looking at the designs for Affnan siphon and I dont see the difference between Affnan and Bell siphons.
they both have a media guard.
they both have an outer creating a pressure barrier. (one calls it a bell, the other doesn't)
they both have a standpipe and a reducer that creates suction after the water spills into the standpipe.

they seem like the same idea to me.

thanks for the diagrams

[TCLynx]

Actually put a T instead of an elbow at the top of the vertical pipe in the fish tank and you get a SLO (solids lifting overflow) drain rather than a siphon and comes with a built in overflow.  Be sure to use appropriate grates to keep your fish from visiting the inside of your plumbing or sunning themselves on the gravel in the grow beds.

Leo White Bear said:

Get rid of the vertical pipe in the fish tank.  If power should go out, you will be siphioning all the water out of your fish tank,   It doesn't take long for this to happen.

[TCLynx]

William, you are right that trying to do a SUMP/Grow bed is going to add some to the complexity of the system water level balancing and the Easy way is to go with a sump tank big enough for the job.  This also allows more water in the system to help with system water chemistry and temperature stability.

But on a side note if one was going to do a sump bed or something of the sort.  Speed of flood and drain doesn't matter that much so long as there is flood and drain happening.  (except that if you have a very large siphon suddenly flushing onto the surface of the gravel in a grow bed, you will wind up with lots of splashing and wet surface gravel that is getting that large flow.

But other than that, the idea that you need a fast drain to pull air down into the bed really doesn't pan out.  AIR is going to be drawn down into the bed no matter how fast or slow the bed is draining.  Actually the fast drain only seems to provide extra aeration to the tank it is draining (splashing) into, and ONLY while it is actually draining.  The fast drain also has the side effect of sucking a bit more of the very fine suspended solids out of the grow beds and into the sump while the timed flood and drain with the slow drain seems to leave more of those fine solids in the grow beds.

AND, if you are having a really bad time with sump tanks and JUST CAN NOT manage a large enough sump tank to handle flooding and draining all your beds.  There is another option if you are running the pump constantly.  Set some beds as constant flow/constant flood.  As long as you have about 9 liters per minute of flow through those beds, it seems to work quite well for many plants.  BYAP did trials comparing timed flood and drain, constant flood and siphon flood and drain systems and there were only minor variations in how those system did overall.

[Leo White Bear]

Or instead of the Tee, drill a hole in the vertical pipe a few inches down from the elbow.  You still get the SLO, its less expensive (although by a few cents).  But I HAVE to agree with TC, use screening on the bottom of this pipe otherwise you will suck up your fish.  A good way to do this is to check out PVC drain screens, made for bath tubs, they fit into a fitting that attatches to the end of the vertical pipe, You may need to get as reducer from this fitting to your pipe.
 
TCLynx said:

Actually put a T instead of an elbow at the top of the vertical pipe in the fish tank and you get a SLO (solids lifting overflow) drain rather than a siphon and comes with a built in overflow.  Be sure to use appropriate grates to keep your fish from visiting the inside of your plumbing or sunning themselves on the gravel in the grow beds.

Leo White Bear said:

Get rid of the vertical pipe in the fish tank.  If power should go out, you will be siphioning all the water out of your fish tank,   It doesn't take long for this to happen.

[Jim Fisk]

If you have a chop saw you may want to try my method. I go to the bottom of my fish tanks  in 1 1'4" and then into a 90 and across the bottom a few feet and a cap on the end. Then using the chop saw I cut 1/4" (big enough to pass food and waste but not fish) slots across the bottom of that bottom pipe in a grill fashion and strap your Walmart 12" or two 10" air stones on top of that bottom pipe. This draws the waste right to your pick up slotted pipe and greatly helps keep your tank cleaner. Also I use a round rat tail type appliance brush to push down the tee slowly a foot or two, pulse it up and down a couple of inches and then rapidly pull it up and out of the T. This clears out any stuck crud and clears everything.

I do this once or twice a week on each tank. Works really well. You can see a pic at my home page if this appeals to you.