Backyard Aquaponics
A place to discuss aquaponics

I just built a flood and drain system using a bell siphon. The window I had to put it in front of for maximum sunlight is close enough I can hear the siphon at night. So I was wondering if it would be safe for the fish to turn off the system at night. I could possibly use a traditional aquarium filter if there's fear of throwing the numbers too far off during those 7ish hrs.

Not sure how big your system is but if you had an airation pump I would leave it on.

It is safe for the fish if there is enough dissolved oxygen in the tank water but you do not want to dry out(kill) the beneficial bacteria in the growbeds.

I do have a good size aerator stone that should be more than enough and I do plan on leaving that on 24/7. What I wonder is if the ammonia levels could become dangerous in that time period. I'm using two fairly heavy duty totes. A 22.5gallon(85L) one for the tank that has around 21 gallons and a 14.5 gallon(55L) for the GB. I'm using gravel as the medium and before flushing it holds about 2.5 gallons (9.5L) of water. I goofed a bit when I made the siphon so it doesn't drain down as far as I'd like. Maybe that extra water that remains would be enough to keep the bacteria happy? The type of gravel I'm using is fairly small; I'd say it averages around 10mm and it tends to hold about 1/2 Cup/Quart after being drained thoroughly.

I shut down my system at night - I have a light sensor that shuts it down automatically when it gets dark and turns on at first light. Water is aerated 24/7. 3/8" (10mm) gravel. Never had a problem with the fish and the plants never show signs of wilting. I don't have a high stocking density however.

Awesome thanks for the input! It's funny you're on this forum (Web4Deb) because your video on Youtube was one of the reasons I decided to build this little system as a prototype before I go large scale in a small greenhouse Approximately what is your stocking density?

Ya - I came accross his video on youtube before finding this place also. Neat greenhouse!

aw...you guys make me blush. Thanks!

I keep around 20 3" goldfish in the 150 gallon tank...they're still growing! Last summer the nitrate levels were a bit low when the cukes and tomatoes were going full blast so I would supplement the system with a bit of peeponics. Just don't tell my wife! She has a hard enough time accepting the fact that the fish waste is ok!

Tell her that she expels CO2 that plants(including vegetables that she eats) consume.

Just a note about shutting down at night.
While you do the initial cycle up, I would advise running it as much as possible to help get the bacteria going for those first six weeks or so.

After that, it will depend on your stocking density and feed rate as to how much ammonia might build up over night. If in doubt, take to doing ammonia tests first thing in the morning to see if you are threatening your fish.

lol 'peeponics', that's great. I was actually wondering the other day if I could jumpstart the system that way to get a bit of ammonia in to feed the bacteria I've heard of going with 1 fish per gallon and 1 fish for every 2.5 gallons. I plan on using small fish (not food) so I was thinking of stocking 10-15 fish and growing as many plants as possible in the GB, is that too many or would it be able to handle over 15? Thanks for the tips on getting a good culture going and that's a great idea to do an ammonia test asap in the morning. I've got lettuce, tomato, and spinach seedlings starting so after they get decent size I'll transplant and cycle for a while with just the plants, from what I hear that's the safest way to go about it. The last thing I wanna do is hurt a living thing so I'm gonna make sure everything is perfect before introducing the fish.

Pee ponics works just fine and is a great way to cycle up a system before adding fish. Fishless cycling is far less stressful than worrying about killing the poor little things or starving them on the other hand.
http://backyardaquaponics.com/forum/viewtopic.php?f=18&t=2534

As TCL says, for the first two months of system operation (especially if stocked with live fish) run everything flat out. After that, you can start to tinker with shutting down pumps. Always leave air (preferably battery backed up as well) running continuously.

I have mine running from 6am-9pm and then shut off. Air pumping 24/7. All good so far!

Just a quick question:
Why is it necessary to shut down over night when algae consume DO(Dissolved Oxygen) and return CO2?
Is this for cost saving?
Or for fatalistic pleasures?