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flood and drain times?
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Author:  Springa [ Oct 31st, '07, 18:57 ]
Post subject:  flood and drain times?
I have been trying to find out what flood and drain times are ok. I know the info has gotta be here but i cant seem to find it.

My single grow bed is flooding in 9 minutes and draining in 4.

Is this ok or do i need to adjust it?

springa
Author:  monya [ Oct 31st, '07, 19:33 ]
Post subject: 
I reckon you could stretch the drain time out a bit. My old system ran about 20 minutes to flood and then just over an hour to drain. Depends on how long between floods too, you want the water in contact with the gravel for a decent amount of time.
Author:  steve [ Oct 31st, '07, 20:21 ]
Post subject: 
don't think it matters too much really. cant remember exactly but mine was on something like a 2minute flood 45 second drain :shock:
Author:  janethesselberth [ Oct 31st, '07, 20:32 ]
Post subject: 
My system floods and drains with about the same frequency, Springa. I suspect that keeps it a little too wet for some plants, but my ferns, peace lily and butterfly ginger are loving it.
Author:  Springa [ Nov 1st, '07, 06:24 ]
Post subject: 
thx for the replies,

monya i run the pump all the time atm except night, so its flooding & draining constanly.


springa

ps your stakes will go in the mail tommorrow, only problem i have only been able to make 2, so i thought id seend them and 2 more next night shift in four weeks
Author:  monya [ Nov 1st, '07, 06:31 ]
Post subject: 
that's brilliant!

yeah, if you are running all the time, that changes the equation.
Author:  hawaiinewbie [ Nov 6th, '07, 05:57 ]
Post subject: 
I run 15 minutes on 45 minutes off form 6am to 10 pm. Its off at night. It takes my GBs about 20 minutes to drain completely. Seems to be working OK. I might experiment a bit later to see if I can get faster growth.
Author:  rpondpa [ Nov 6th, '07, 07:40 ]
Post subject: 
My timer is on 30 minute increments, so the pump supplies water for 30 minutes and turns off for 30. It probably takes about 5 minutes for my grow beds to drain.

Do I need to adjust this?

I'm just starting to grow some things, so I can't yet tell from the grow rates. The basil seems to be OK but the parsley has not done well. Wheat grass seems to survive anything.

Thanks for your response.
Author:  shekman [ Nov 6th, '07, 07:48 ]
Post subject:  Re: flood and drain times?
Hi all,

I am just wondering, leaving the pump turn off at night, wouldn't it kill the bacteria in the GB?
Author:  janethesselberth [ Nov 6th, '07, 09:06 ]
Post subject: 
I run continuously, but the beds flood in roughly 8 minutes, and then drain in 5 minutes. I have been thinking about slowing it down slightly. Some plants seem to think that's too wet. Either that or that they need more light.

Leaving the pump off overnight shouldn't hurt the bacteria, however, remember that ammonia will build up, and oxygen will decrease unless you keep some air going. Oxygen levels are naturally lowest right before dawn, so leaving pumps off overnight could earn you a fishkill if you are stocking densely.
Author:  steve [ Nov 6th, '07, 09:48 ]
Post subject: 
Shekman, you're prolly thinking along the lines of a cannister filter for an aquarium. Becasue they're "flooded" the water will become anerobic and prolly kill the bacteria. A gravel growbed that is fully drained yet moist would, imo, have near O2 saturation.
Author:  monya [ Nov 6th, '07, 09:54 ]
Post subject: 
I have had GB's off for 24 hours or more accidentally with no ill effect on bacteria.
Author:  shekman [ Nov 6th, '07, 14:17 ]
Post subject:  Re: flood and drain times?
Thanks for the replies,

I was thinking nitrify bacteria population will start to reduce once the GB is drained due to lack of food to process and GB start to dry out.
Author:  EllKayBee [ Nov 7th, '07, 06:58 ]
Post subject: 
A theory was put forward for turning off pumps that this would reduce the amount of heat lost when the water was pumped through the media...the media cooling down quickly in the cool night temps and sucking out the heat from the water.

I tried this with an auxilliary air supply to keep DO levels up, the problem that occurred was the nitrite level rose to 0.5 (I didn’t pick this up until I noticed my fish were acting differently)...with low winter water temps, it took a further 2 weeks before the nitrite returned to zero.

So there are a few variables to take into account by removing the pump flow from a recirculating system for long periods of time regularly.

Quote:
...so leaving pumps off overnight could earn you a fishkill if you are stocking densely.


I think low DO levels due to the pump being turned off at night was the cause of forest losing all her SP fingerlings early this year...she initially had the pump going on all night, then changed to it being off from 10pm to 6am (with no other supplementary air supply)...her fish lasted 2 more days.
Author:  TimC [ Nov 7th, '07, 08:12 ]
Post subject: 
I have always heard that with cannister filters on aquariums it isn't necessarily the power cut that kills your fish but rather when it comes back on....
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