Trials and Tribulations of getting a Flood and Drain System Up and Running

[Richard Kowalski]

Well, It took me a while to get the greenhouse built and the grow beds built. In the beginning of April, I finally finished the plumbing of my system.

It consists of a 300 Gallon fish tank, a 150 Gallon sump tank, a 3X6 and a 3X4 grow bed, a Bio Filter and a Radial Flow filter. I am using Hydroton in my grow beds. I used 1 inch PVC pipe for the plumbing and 1 MAX-FLO 1350 pump. I also built 2 venturi's to see if I could get away with not having an air pump. I thought that the ebb and flow of the grow beds and the added venturi's would provide enough oxygen for the system.

Mistake 1

I filled the system with water and ran it a few days. The first thing I noticed was that the venturi's were not sucking air. No matter what I tried, they did not work. The fish tank water was brown and murky even though I washed the hydroton before I put it into the grow beds. 

Solution 1

I turned off the system and removed the venturi's. I bought an air pump. I did a 50% water change. I started up the system again and the next day the water was crystal clear. There was some precipitate on the bottom of the fish tank. I vacuumed out the debris with a shop vac.

Mistake 2

There was something I did not notice before. The sump tank water level dropped lower than the water pump. I checked the flow rate of my grow beds. they were cycling (flooding and draining) every 15 minutes. I checked the flow of the fish tank to the sump tank. It was 90 gallons an hour. Whenever the grow beds were filling at the same exact time there was a water deficit.

Solution 2

I turned off the system and changed the PVC pipe to a diameter of  2 inches going to the radial flow filter and into the sump tank. The rule is that all of the fish tank water should be cycled at least 1 time an hour. So I need a flow rate of 300 gallons an hour from my fish tank to the sump tank.

Mistake 3

I was very excited to start fishless cycling. I have about 500 gallons of water in the system. I was not about to go cap full to cap full of ammonia to get the ammonia level up to 2 PPM. I shut down the system and just worked with the 300 gallon fish tank. I figured that if I added a little too much ammonia, when I turned the system back on and the rest of the water was mixed in, the reading should turn out ok. I mixed in a 1/2 a cup of ammonia and took a reading using the API Test Kit. It showed .25 PPM. OK. I mixed in another 1/2 cup of ammonia. I took another reading. I was called away so the sample was sitting in the rack. When I came back The reading was off the charts! I thought that maybe the system needed to be cycled. I turned the system back on and waited a day. The reading was the same.

Solution 3

What happened??? How could this be??? I read the API instructions again and realized that I did not wait the prescribed time before I took the reading. You need to wait 5 minutes before the reading is valid. I removed 3/4 of the water in my system. I drained the grow beds and filled them with clean water to try and wash out some of the ammonia there. I cycled the system over night. the ammonia reading is 4 PPM. The water temperature of the system is 60 F. I am going to let the system cycle for a few days and check it again.

Life is a learning experience. I have learned a lot. There is a lot more to learn. I hope this blog will help someone else not make the same mistakes I did.

Regards,

Rich K

[Jim Fisk]

My conclusion after reading your trials and tribs is that you need to do a whole lot more reading and taking notes. I hope you realize it can take 6 mos to a year to get the system stabilized. It takes time to grow the colonies of bacteria. Until then you will see lots of ph, etc. swings. Small adjustments at a time on any additives.

Don't forget to create a bypass loop so you can control all that pump power in such a small system. (a 300gph pump would have been plenty and cost a whole lot less $ to run but you have plenty of pump for tripling the size of your system later) Also IMHO the sump should always be after the filter (grow) beds and that is where the pump should reside and pump the fresh water back to the FT. Now you have 2 places where solids will build up and need cleaning instead of just the fish tank if I am following you right.

@JJ, get past the GB over the FT concept as you enlarge your system if room allows. Mine are even in a separate room on the N side of the GH.

[Jim Joy]

I also over did the ammonia.  Put a 1/4 cup of ammonia in 150 gallons of water.  It took three weeks for the level to decrease enough to measure with my test kit.  The water kit can detect from 0 to 8 ppm of ammonia.  

I learned later to dilute the test water with distilled water to get the level being tested in range.   So, if you use equal parts distilled water and test water, and the ammonia reading is 7, the effective level is 14.   

[Jim Joy]

My biggest mistake so far was building a frame over the fish tank for the grow beds to sit on.  Nice compact setup, but I can't access the fish tank for maintenance or to observe the fish.  It still worked and plants are growing like crazy.  I plan to double the water tank size from 150 to 300 gallons and build a lot more media beds.  But, I won't obstruct the water tank again.

[Bill Swearingen]

Thank you for all of your lessons learned! I'm sure that many more than just I share this feeling.