Backyard Aquaponics
A place to discuss aquaponics

This may help you picture in your mind what role the sump plays!...

Ok, but how do you decide if a sump is needed? It seems if you stay within the 1sq ft of grow bed space for every 6 gallons of water in your FT that a sump may not be necessary in a flood and drain system. How do you decide if a sump is needed, and is there someone on this thread using a bell siphon set up that can speak to this? Also, it would seem if you use a constant flood system that you could keep enough water in the system so that the tank and the bed stay full, but I guess that could be problematic if the pump rate was off or maybe if the power goes out.

Yes, the sump acts as a buffer for the water level.Constant Height In Fish Tank, Pump In Sump Tank, or CHIFT PIST, is the configuration most used by siphon users. Basically, the pump is in the sump tank, it pumps to the highest piece in the system, could be fish tank or grow bed. Then everything is gravity fed from there back to the sump. People will often use a Solids Lifting Outlet, or SLO in their fishtank, and that sort of sets the water level, and keeps the tank cleaner.

Mr. Damage beat me to it!

The sump would be in a system where the flow went fishtank -> growbed -> to sump, then pumped back up to fish tank. (CHIFT PIST (constant height in fish tank, pump in sump tank)) but a standayd BYAP system or most IBC systems dont bother with a sump.

But there is another way, and that's to create a small sump, and another growbed at sump level. This would mean the lower growbed would acta as a sump (reservoir) for the upper grow bed.

If the lower grow bed is set at the same height as the high tide mark of the sump, you flood the bottom grow bed when the top drains, and the top when the sump is pumped out.

Twice the water use for the pumping price of one.

I'm considering adding a sump to my system just because I'm not the most attentive person in the world and sometimes forget to top up. When you have 100 gallon tank and 40 of that gets pulled off to water the plants, you have a good amount of water left in the tank... but when you forget to top off for a week (or two... or three) and only have 60 gallons left in the tank, pulling 40 off to water the plants makes the fishies a bit nervous.

My new (second?) system will be two IBCs with the "fish tank" raised about a foot and the grow beds on the sump. Someone pointed out in someone else's thread earlier this week that the names fish tank and sump tank need not be restrictive. You can put fish in both. One is just a constant height with an SLO, the other is varying height with a pump.

On a mostly unrelated note, I think 'height' is a stupid way to spell any word. I vote for the new spelling of hite.

Also, I'm Affnanian. Siphons all the way, baby!

The use of siphons does not mandate the requirement for sumps.

The decision to install a sump is dependent on the amount of water you have in the system and the location of that water at every moment during all cycles. If you have a pump and a FT, there will be a "low tide" point which will be the higher of, a) the water level in the tank at which the pump will lose suction, or b) the water level of the fish tank at which fish will become stressed. If the amount of water pumped out of the FT to attain this level is not sufficient to flood the GBs then you'll need to add more water (or obtain a FT with a different shape, but let's assume you want to keep working with what you already have). The other way to think of this; if you flood the GBs and there isn't enough water for the fish and the pump, then you need a sump.

The issue can be complicated a little further by the pumping cycle; it is easy to have constant water levels throughout the system by not allowing the GBs to drain down at any time (some people don't like this as they (wrongly) think the plants will drown, but if the water is well oxygenated this doesn't adversely affect the plant growth and the water is not left standing for too long), and you can either have the pump running continuously or cycled, each has its own benefit and both methods have potential to save the owner $$$. If you are going to have a changing water level anywhere in the system, then at least one component will require ullage to be able to receive that water, this is where a sump is installed (even in continuously flooded systems, to allow the GBs to be drained down without wasting that water or require re-filling, otherwise the sump spends the majority of the time (nearly) empty).

Draw your system on paper and look carefully at where your water at every moment during all cycles, not forgetting to account for your inattentiveness. If you spend the time to plan well, you'll save time, money and fish later.

If you are prone to forgetting to top up as often as you probably should, then you should spend a commensurate amount of time planning contingency measures and installing safety features, rather than being distracted by less important facets; siphons (of any design) don't work if your system is dry!

note to self... ullage

Nice.

I love it when I find a word that's completely necessary, but has escaped my attention for so many years.

Thanks bunson.

Another question. It seems from watching Affnan's videos that you don't need as strong a pump if you are using a bell siphon as opposed to a timed ebb and flow set up. Is this true? It's hard to tell, because Affnan refers to the pumps by wattage and not gph. What pump size would be recommended for a 55 gallon FT with a 67 gal crowned and ~25gal sump. Top of grow bed will be about 3.25' above the pump in the sump tank.

Yes it does.

The pump size on a timed setup is probably going to need to be larger, but not a whole lot larger. For example, if you go with a 15/45 timed setup, you'll need a 100 GPH flow at head (not the same as a 100 GPH pump... some pumps have significant losses at 3 feet) and with an Affnans siphon, you'll want about a 75 GPH flow. The siphon can be tweaked to work at a lower flow than that, but you'll want to run all your water thru the grow bed at least once an hour.

The timed 100 GPH comes from: (grow bed volume * .4) * 4

The rule of thumb is that the media takes up 60% of the grow bed, and you'll need to fill that in 15 minutes instead of an hour.

There are hundreds of systems on this forum where siphons are employed without that system having a ST installed. When I feel like tinkering, I put my siphon back in my system, GB sits on top of FT, GB fills and siphon kicks in and drains the GB back into the FT; no need for a sump. I'll reiterate, the requirement to have a sump is mandated by the volume of water required in a system, and has nothing to do with the plumbing configuration.