Backyard Aquaponics
A place to discuss aquaponics

Novaris.... if your desire to run solenoid valves is related to concern about exhausting your sump or fish tank.. consider....

If you setup your system as a "CHIFT PIST" system.... that's a "constant height in fish tank, pump in sump tank"..... then....

Your fish tank can't run low on water.... as the term "constant height" implies... it will only lower to the level of the standpipe....

So your sump wont run dry either.....

As you are/would be pumping back to the fish tank from the sump "continuously" and the growbeds are returning water continually....the level in the sump tank should also remain relatively constant, maybe varying about 1/3 - 1/2 at most....

Worse case scenario.... sump pump fails....

The chances of all three beds siphoning and returning water back to the sump are minimal... it can happen, but in reality seldom does...

So chances are that all three beds will never be full at the same time.... so the chances of all three beds (750ltr) activating their siphons when the pump fails.... leading to the sump (500ltr) overflowing.... are near zero....

Of course if the sump pump isn't pumping... then the level in the fish tank wont be sufficient to overflow and supply the growbeds...

So in reality, in the worse case your fish tank level will be fine.... your growbeds may have a varying amount of water left in them ... and your sump will have an amount of water left in it....

Don't see the need for "valves" really..... and this all assumes that your actual growbed capacity .... as in water capacity to fill them... is actually 750ltrs...

If that figure was derived from the growbed dimensions... then it represents the total capacity of the growbed..... but not the capacity/volume of water in a "flood" cycle...

Because the media typically takes up about 50-60% of the growbed capacity.... the water fills the spaces between the media.... typically 40-50%...

See you've already worked your "flood" out to be 300ltr... don't see the need then to "sequence" them in "series"... so no need for the valves....

Thanks for the input RupertofOZ, I have been trying to relate to what you said and I think the hitch is "growbeds are returning water continually"


I have designed a chift pist system, pump to fish tank, tank overflow to GB and autosiphon to more rapidly empty the GB to sump. If I did this I see the chance that 290L in one GB 150 in another and 60 in the third, my sump is dry as no siphon has kicked in. Fish tank level is still Ok but circulation is stopped i.e. oxygen level drops.

Am i missing something?

I agree with novaris. Also if the three growbed syphons kick in at once, you'll have 900L of water rapidly draining into the 500L sump. If the pump can't keep up, you'll lose water.

I think chift pist with autosyphons needs a big enough sump to handle a full flood.

Steem, you're correct that "if" all siphons kick in at the same time... potentially the total volume could exceed the volume of the sump tank....

But remember, that the sump tank is pumping back to the fish tank continuously....

So I don't see it as a problem really.... the chances of all three siphons kicking in at once is slim..... and the sump pump would have to have stopped to result in an "overflow"...

Chances of the growbeds all being full.... the sump pump failing at that point... and all siphons kicking in at once......

Very unlikely IMHO.... much more likely the sump pump would fail at a given point.... meaning it wont be raising the level of the fish tank to initiate the overflow to feed the beds....

So they're unlikely to all be "full"... and all "siphon" at once....

Similarly Novaris.... yep the beds could be thoretically filled to the values you suggest.... but I doubt that thwe sump would be empty....

The fish tank tank standpipe would have stopped supplying the beds.... and chances are that at least one siphon would have activated before the beds got to the theoretical levels you suggest.... hence there'd be water still in the sump... still in the beds.... still in the tank..... as soon as either the sump pump supplies water to the fish tank... to growbed... to siphon... to sump....

The "theoretical" situation resolves.... the beauty of "CHIFT PIST" ....

Make sense??

Sorry, I still don't like it. I need to point out that the sump pump doesn't have to fail for there to be a problem.

Think about how many cycles there are a day - circumstances leading to problems would have to be very unlikely indeed in order to have a reliable system. Say there's 20 cycles/day - if everything is fine 999 times out of 1000 then there is a problem once every 6 weeks.

Another situation is if no bed is more than 1/3 full, you'll need a spare 600L (200 for each bed) in the sump to get the next drain cycle to happen. Since you only have 500, none of the beds will ever fill enough for the syphon to kick in, and the cycling will stop.

This is tongue in cheek Rupe, but my experiences with flooding is that I've been amazed how many different ways you can end up with water on the ground instead of in the system

The rules of flood club:
1. You do not talk about flood club.
2. You do not talk about flood club.
3. If there is a way for a flood to happen, sooner or later it will happen.
4. If you're going to be away from the system for a while, this is when it will happen.
5. Rules 1 and 2 do not apply to the forum
6. Pictures f&f loves pictures

Cheers
Stephen

On the last 2 posts .One thing i have found with aquaponics is if[ it could happen] it probley will

[quote"Steem"]
Another situation is if no bed is more than 1/3 full, you'll need a spare 600L (200 for each bed) in the sump to get the next drain cycle to happen. Since you only have 500, none of the beds will ever fill enough for the syphon to kick in, and the cycling will stop.[/quote]

But Steem... the grow beds are filled from the overflow of the standpipe in the fish tank (CHIFT PIST)..... not from the sump....

The sump is pumping continually to the fish tank.... constantly supplying, a relatively small volume of water to the growbeds by "overflow"..... the growbeds are constantly filling and draining and constantly filling the sump... which is constantly filling the fish tank etc....

Les, chime in here mate..... I think that Les, for instance, will verify that the sump level only varies by about 30% (from maximum).....

Even if the growbed siphons ALL blocked ... the growbeds are unlikely to overflow... because the sump would only provide less volume (500ltr) to the fish tank, and hence to the growbeds, than the total capacity of the growbeds.....

It's hard to see a "frozen" moment in time where the continuous process breaks down to the point of compromising a complete emptying of the sump... unless ALL siphons fail to activate....

Possible I supppose... but highly unlikely IMHO...

Clear the siphon problem(s)... and the sump fills.... tank fills... overflows to the growbeds.... cycle is restarted....

Hi les why not try an ordenary float valve set on a moving arm height adjuster in the sump they will work under water [high level sump ] and when the water drops [low level ] it will open and let water in [dont worry about bio film on the float] or the inside theres only fresh water in there, It will not make a difference each cycle you will only be adding a small amount

Yep, but the tank is constant height so if the beds need 600L then that water has to start in the sump, which tops up the ft which then overflows to the beds...so if the growbed is not full, the only way to fill it is to have water available in the sump. In other words you can take the tank out of the equation...I think


Good point, I'm only going on theory. If Les's system has multiple gb's that have a total water capacity greater than the sump, then whatever he's done to make it work is one solution
I'll leave to someone with experience in such matters to comment. I just thought that novaris' combination of volumes meant that the three syphon cycles would have to be quite close to evenly spaced all the time in order to avoid running out of water. Apologies if I miscalculated

When I was thinking on sys design, I looked at valves... and most valves alone won't get it, you also need control switches. But with my little "KISS SYS" I'm not ready for them until I'm prepared to plunk down some real commercial money.

I only post this cuz I haven't seen anyone here talk about controls, only valves and that's really only 1/2 the picture/answer. here is an ok one, i was looking at.
http://www.engineeringtalk.com/news/srl/srl100.html

There are loads of 12V controls too, that work always opened/closed until "contact" is made, "contact" being the water level. I know Hydro guys that use this style with timers. IE. low level DWC or SWC with a flood cycle for the newly planted roots on timers.

When there is no power to the switch, it ignores the water level and stays open/closed controlling the valve. When energized it closes/opens until water level makes contact again, now set this to a timer.

I seem to remember ppl leaving hoses turned on and forgetting about them when filling them, flood water getting under sump tanks and popping them and all sorts of things Rupe, at some time they will all be near to kicking in and cause flooding (murphy )

My beds trigger in sequence, so there is a slight difference...each bed is ~500litres capacity (up to the high water level mark)...the water transfer is ~160 litres/GB (33%)...my GBs do not totally empty, there is about 20mm depth left.

If you work on 40% water to 60% gravel, this will give a good safety level for the amount of water to be dumped back into the sump for each GB...then calculate the minimum amount of water at low tide to keep the pump working...from this you have a minimum sump tank requirement.

Finally work out your daily water usage (or weekly if that fits in better) and make sure the sump tank can hold sufficient to carry over for the period.

Hope this is of some benefit (or have I gone totally off topic and confused everybody )

Thanks F&F. taking that into consideration also, just put up the valve and price up to give ppl some idea of the costing of these..multiply by the number of beds that require one and it gets kinda expensive

Since the system will only have one GB to start with I think I might just see how it goes as I add the other GB's in over time. In the meantime I will experiment with my (low cost) idea for serial filling.

I have to agree with Steem here.

My front system had to be converted from syphons to constant flow due to the 4 beds occasionally coming into alignment, causing all the water to be pumped into the 4 almost full growbeds, stopping procedings in a rather noisy non pumping way

Chift Pist as well.

Sump capacity must be equal or greater than the growbed water capacity.