Timing for drain and fill

[David E Harnish]

I have seen numerous recommendations for how long to take to drain the beds, and then for refilling them. Is it appropriate to have the pump running all the time, and control the flow into the grow bed (s)?

Or, is it better to have them (pumps) on a timer? I do not have a sump. So far just one tank and one grow bed, with plans for two more of each.

Thanks for any input.

David

[Fred]

I prefer to run my pump continuously.  This helps keep the tank and grow beds flowing and avoids build-up of solids.  It also increases aeration and should increase the life of your pump.  You also avoid having to mange a timer for the pump.

On the downside, your electric use will be higher and if the outside air temps are cold, your grow beds will likely chill your water. 

[Alex Veidel]

Well Fred, I think you could just about split this community down the middle on the continuous flow vs. timed flood and drain argument. Personally, I love bell siphons, but a lot of people say they're unreliable. I haven't had the same problems others have had.

You want to shoot for a 15-20 min approximate flood and drain cycle.

Fred said:

I prefer to run my pump continuously.  This helps keep the tank and grow beds flowing and avoids build-up of solids.  It also increases aeration and should increase the life of your pump.  You also avoid having to mange a timer for the pump.

On the downside, your electric use will be higher and if the outside air temps are cold, your grow beds will likely chill your water. 

[George]

David, once you add more beds, you will eventually need to use either a timer and an indexing valve, or add a sump. Otherwise, when you fill multiple beds at the same time, you'll be also lowering the water level in your tank.  Keep reading and try using the Search feature to find the information you need.  Once you understand the options, you can decide what to do.

It doesn't seen to matter how long it takes to flood, or drain.  What does matter is that you have plenty of oxygen in the water.  

[Jim Troyer]

Bell siphons are fiddly in my humble opinion. 

Running the pump all the time is unnecessary, expensive and wears out the bushings many times faster in my case. 

I'm running timers and a double stand pipe on several systems.  I run the pump a 1/2 hour out of 4 hours (3 hrs/day) and everybody is happy.  The short stand pipe is 3" tall (min water depth) and the other is 7" tall (approx. max depth).

My media/plants are in 2 liter soda bottles cut off where they start to neck down.  Large slots are required in the lower 1/3 for efficient water flow through the bottles which is the key to this method.  I love being able to move my plants around too.

I have 40 adult tilapia in 700 gallons of water. 

It all works, it's just bacteria/fish/water/plants and worms ...anyway you choose it seems to work

[Fred]

When you shutoff your pump, how do you ensure each grow bed is drained if you're using a bell or loop siphon?

I have composting worms in my grow beds and I would be worried about leaving a grow bed 90% full.  I also don't think this would be good for the plants.

[Jack Rife]

David I use the CHOP system running 24/7 with bell siphons in 4 grow beds with one grow bed draining through a DWC raft type bed and have no problems with this type system for over a year. Still using the first pump.

Jack Rife

[David E Harnish]

Thanks for the additional input.  I have now added the other two systems, so have three IBC tanks cut off so I have 150 gallons in each when all beds have drained. I have three grow beds one each on top of the "tanks". Full they each take about 25 gallons, so the fish tanks drop to 125 gal. each which does not seem to be significant. I have all three interconnected  via the drain valves at the bottom of the tanks. I have bell siphons which work great to drain the beds in about 4 minutes.. George mentioned an indexing valve. What is that, and how is it used?

 David

[Jim Troyer]

@ David: An indexing valve switches water flow from a single source from grow bed to grow bed.  It allows you to run the pump constantly and fill one grow bed at a time.  While the first GB is draining; the second fills and so on. Handy if you run a wimpy little pump also allows you to function without bell siphons.

@Fred: Leaving the water semi-full does not seem to be a problem for plants over night. The worms can live in water but will climb above the water level for a breath if they are stressed.   I know a commercial grower that runs a constant flow system and does not ever drain the grow beds.  I use a timer, on 15 on/ 45 off and shut down from 4pm to 9am this time of year.  During the summer months, I run the pump 30 minutes, 3 times each night to stir the water for the fish.  I do not provide any aeration in my systems (15gal/fish) as it is unnecessary when you don't overcrowd.

[Alex Veidel]

Wait, an indexing valve doesn't require an interruption in the flow of water to switch from one growbed to another? 

Jim Troyer said:

@ David: An indexing valve switches water flow from a single source from grow bed to grow bed.  It allows you to run the pump constantly and fill one grow bed at a time.  While the first GB is draining; the second fills and so on. Handy if you run a wimpy little pump also allows you to function without bell siphons.

@Fred: Leaving the water semi-full does not seem to be a problem for plants over night. The worms can live in water but will climb above the water level for a breath if they are stressed.   I know a commercial grower that runs a constant flow system and does not ever drain the grow beds.  I use a timer, on 15 on/ 45 off and shut down from 4pm to 9am this time of year.  During the summer months, I run the pump 30 minutes, 3 times each night to stir the water for the fish.  I do not provide any aeration in my systems (15gal/fish) as it is unnecessary when you don't overcrowd.

[David E Harnish]

What are some recommendations for an indexing valve?

A google search lists a FIMCO Hydro indexing valve which seems interesting.  As I see it, the valve will stay open as long as there is water pressure to it, so if you have the pump on alll the time how does the valve know when to switch to the next bed?

I am about ready to add fish to my system. I live in Hayward, so it would be easy to come up to Sacramento to get them.

I just want to start in one tank, so how many fish (Talapia) should I have for the 150  Gal tank? 

Does any one there have any Talapia for sale - or give away if you have too many?  Hi Hi.

David

[Jim Troyer]

check with TC lynx in this site regarding her indexing valve.  I believe she sells them.

[Scott Roberts]

David - Tilapia are not allowed in Northern California. In addition, the winters require lots of supplemental heat to keep them alive, so they're not the ideal fish here.