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Hi,  we have three grow beds with one sump.  We originally had them set up to each fill at a different time, twice an hour.  This worked great for the first month.  Now every day or two the beds end up on the same cycle, which means the sump level gets too low and we have to add water - have been adding 5 gallons at a time, which we keep pre-heated and ready to go, but really, this is a pain to constantly worry about whether or not the pump is sucking air.  Plus every time we add water it changes the ph balance.  For some reason, despite being the same sized beds and having the same amount of media (clay pebbles) the beds do not fill at the same rate.  So even when we try to adjust the water flow to get them on different cycles they end up on the same cycle over time. 

Any suggestions as to how to keep the beds filling at different times?

Thanks.

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Are  you running with a Constant Height One Pump (chop) system where water is pumped from your sump to a manifold and into your GBs then gravity flows to the fish tank and then through a normal level overflow and or a Solids Lift Overflow (slo) back into the sump?

Besides losing water from normal evaporation, these or similar systems might periodically run low if there has been a change to the height of the fish tank, a partial blockage built up in either the GB media, a GB syphon, or the FT to sump piping. Or if there has been a build up of solids in the sump or a sudden removal of them from the GBs or FT.

It would be really difficult to set 3 GB up to always f&d at the same intervals due to each bed gradually building more or less solids, roots, and bio materials.

I hope this helps locate where the water IS bunching up instead of where it should be in the sump. If not, it might indicate a hidden leak somewhere.

Hi Glenn,

Thank you for your response.

I am not sure what you mean by manifold, but basically the water is pumped from the sump to the fish tank and from the sump to the grow beds.  Water goes back into the sump from the fish tank and from the grow beds.  I will check to see if there is a build up of solids, but we have only had the fish a couple of weeks and we just cleaned the filter on the pump so I don't think that will be the cause.  Can you think of anything else?  Maybe some trick to keeping the beds cycling at different times?  And yes, we are loosing a lot of water to evaporation too.

There is what is known as indexing valves that can be plumbed in to direct flow in a sequencing fashion. The way they work basically is when flow stops passing through one port, a mechanical mechanism causes it to jump to the next position and flow is then directed through another port and direction ands so on. These can be very simple mainly when two GBs are in use and only one stream needs to flow at any one time. BUT beyond that, they aren't simple. There are electrical ones but there again, they can and do fail. 

I prefer to keep it simple and let the beds cycle by filling them with a constant flow and emptying them as soon as they are filled. I try to keep the pump sized to allow 4 cycles to each bed per hour. I would not divert water pumped from the sump back to the FT because the GB is the normal bio filtration and until it passes through the media in the beds and unless it has cycled through another filtration section it might not be fit for the fish. I like to keep my main fish tank at a constant level and only over flow from it to the sump and filtration sections.  The only thing required is a constant FT level and a large enough sump to hold enough water to fill the grow beds and any other equipment that drains into the sump. Should power or pump fail, there must be enough room in the sump to hold everything above it. Not the FT water below its normal level which should be constant even during outages.

I lose about 5% of my total water volume weekly to normal evaporation and plant transpiration. Anything more than that I would suspect as leakage, high temperature, or misuse.

For more information about indexing valves, I recommend you contact a member here named TCLynx or read what she has written on the subject.

http://community.theaquaponicsource.com/profile/TCLynx

I originally had the same problem, which I bypassed by installing a larger sump tank. There's nothing wrong with your media beds, your water just isn't flowing into each bed at the exact same rate. Ever be at a red light and pay attention to everybody's turn signals? Sometimes they'll all look like they're lighting up at the same time, and a couple seconds later they'll be blinking at random times again. The timing of each light is just barely different, so they don't all click on and off at the same rate. Same for your growbeds.

Indexing valves require the flow of your water to be stopped completely in order to change from one direction to the next, so, they only work for timer based pumps, not constant flow.

Glenn said:

There is what is known as indexing valves that can be plumbed in to direct flow in a sequencing fashion. The way they work basically is when flow stops passing through one port, a mechanical mechanism causes it to jump to the next position and flow is then directed through another port and direction ands so on. These can be very simple mainly when two GBs are in use and only one stream needs to flow at any one time. BUT beyond that, they aren't simple. There are electrical ones but there again, they can and do fail. 

I prefer to keep it simple and let the beds cycle by filling them with a constant flow and emptying them as soon as they are filled. I try to keep the pump sized to allow 4 cycles to each bed per hour. I would not divert water pumped from the sump back to the FT because the GB is the normal bio filtration and until it passes through the media in the beds and unless it has cycled through another filtration section it might not be fit for the fish. I like to keep my main fish tank at a constant level and only over flow from it to the sump and filtration sections.  The only thing required is a constant FT level and a large enough sump to hold enough water to fill the grow beds and any other equipment that drains into the sump. Should power or pump fail, there must be enough room in the sump to hold everything above it. Not the FT water below its normal level which should be constant even during outages.

I lose about 5% of my total water volume weekly to normal evaporation and plant transpiration. Anything more than that I would suspect as leakage, high temperature, or misuse.

For more information about indexing valves, I recommend you contact a member here named TCLynx or read what she has written on the subject.

http://community.theaquaponicsource.com/profile/TCLynx

Thanks Alex.  We increased the amount of water kept in the sump so even if all three beds fill at once, there is enough water to cover the pump.

Alex Veidel said:

I originally had the same problem, which I bypassed by installing a larger sump tank. There's nothing wrong with your media beds, your water just isn't flowing into each bed at the exact same rate. Ever be at a red light and pay attention to everybody's turn signals? Sometimes they'll all look like they're lighting up at the same time, and a couple seconds later they'll be blinking at random times again. The timing of each light is just barely different, so they don't all click on and off at the same rate. Same for your growbeds.

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