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Flood & drain timing
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Author:  jimmy_d_ward [ May 18th, '07, 06:51 ]
Post subject:  Flood & drain timing
Hi all, new member etc

Have goldfish tank pumping into two 30-litre growbeds in a flood & drain system.

15-minute pump cycle (growbed fills in 2 minutes, so is completely flooded for about 13 minutes)
75-minute drain cycle (growbed drains within about 10 minutes, so is completely aerated for about an hour)

This cycle repeats continuously.

What do you think? More flood-time? More dry-time? Slower drain?
Author:  janethesselberth [ May 18th, '07, 08:34 ]
Post subject: 
Sounds nice...but it all depends ;)

In any system, you need to consider how often the volume of the fish tank turns over, and how wet the plants are. If you have a high volume of fish, you need to turn the tank volume over more often to clean the water and increase dissolved oxygen. For higher stocking volumes, 3x per hour would not be too high. At the same time, you need to balance how wet the roots of your plants stay.

Are you just setting up? If so, try it like you describe and see what happens with water quality and plant growth.

Are you having problems? If so, what?

...And welcome, Jimmy!!!
Author:  RupertofOZ [ May 18th, '07, 08:45 ]
Post subject: 
Welcome Jimmy.... as usual Janet's advise is sound.... basic rule of thumb... see how you go.... but pay heed to the advise of amount of fish and tank volume turnover
Author:  jimmy_d_ward [ May 18th, '07, 12:57 ]
Post subject:  Re: Flood & drain timing
Hi, thanks for the fast responses!

I've got the system set up already, has been running since Monday night.

Timing is achieved via a digital timer-switch, but the maximum number of on/off sequences I can program per day is 20. Will have to invest in a more hardcore timer switch if I am to cycle the water through much more frequently than once per 90 mins! I think I need to have it on more like a 20-minute cycle, i.e. 5 mins flood + 15 mins drain, then straight back into flooding after it's lost its water, without having time to dry the roots out. Okay, off to the electrical shop...

BTW it's a 60cm tank (approx 60 litres). 15 small goldfish + 2 "Australian rainbows" (same size as the goldfish).

Will eventually get around to posting some pictures of the system.
Author:  earthbound [ May 18th, '07, 14:55 ]
Post subject: 
Hey Jimmy,

You can pick up very cheap and reliable times from most department stores that should do the job, they have 15 minute intervals that you can either switch to off or on, little pins that you push down... I have my system set to run for 15 mins, then off for 45mins, continuously over 24 hours.. I think the last time I bought them was from "B" and they were about 7-8 bucks for 2 of them..
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