i spent a lot time about 2 degrees south of the equator where the days and nights are about the same length. the seasonal variations in  the length of day light in the northern hemisphere has always thrown off my internal clock. the darkness in the day still confuse me but I noticed something over the years – the dark days suddenly start getting brighter. i now know this  period is the winter solstice when the sun seems to stand still before starting to move in the opposite direction. it also means that the longest night and the shortest day of the year is come and gone. i have found that this is a time to  begin new things – so i figured why not start some data collections


in our office is a 5000gal fish tank that feeds a 4’x8’x1′ gravel based grow bed that has a 150 gal fish tank sump.

bigGrowbedit has been running smart on a v2 controller for a while, but i was too lazy to dig up the gravel to embed the grow bed water level gb sensor. so i was motivated by the new direction around the sun and dug up the hole in the gravel shown below using my bare hands – the water was freezing, 13 degree’s.

diggingGravelonce i got to the bottom of the grow bed, i add two 1′ pvc pipes. since i am always experimenting, i put one with a drilled end cap and the other without one as show below. my biggest worry is root intrusion – roots are amazing and sneaky.

bottomSenesor1 bottomSenesor2

i positioned the pvc pipes touching the bottom slighting away from the irrigation tubing for maintenance as shown below. my fingers were frozen by now so i finally remembered to put on gloves.

sensorInGrowbedand covered my hole back with gravel. i removed the gloves again because i like the feeling of wet pea gravel on my hands and like the intimacy of every rock.

sensorCoveredWithGrowbedthe two pvc pipes will hold the infrared distance based sensor and a total dissolved solids sensor. the infrared distance sensors are fun and i use them to reflect an ir  beam onto the water surface in the grow bed so i can measure the level of water in the growbed using triangulation. this is fun for me because i like to look at reciprocating flood and drain cycles – i think it is the biases of the systems heart beat. this is shown below. you can see the infra beam glowing on the sensor. the sensor mounts on 1′ pvc slip connector which then mounts onto of the longer pvc pipe.

gbLevelIRsensorthe other pvc pipe is for the tds sensor from altas scientific . i have  ph and tds sensor in the fish tank.  but since my sensor circuits are not isolated electrically the sensors affect one another’s accuracy. for now i isolate them by putting the ph sensor in the fish tank and the tds sensor in the growbed. this sensor is show below. in the next week or two i should  integrate the full water quality kit env-sds using the tentacle shield from whiteboxes the tentacle shield hosts altas electronics with isolation for clean water quality readings. this means i can drop all the ph, tds, o2 and redux probes all in the fishtank without the probes affecting one another

gbTdsSensorboth sensors are show below inserted into the pvc pipes.the tds sensor touches the bottom of the growbed where there is always at least 1′ of water.

ifdistancetds sometimes ir reflections don’t work very well with water, so i cut a disk of plastic from a coffee cup and drop this inside the growbed level sensor pvc pipe.

macCupCutoutboth these sensors then connect to the v2 smart controller as show below:

kj_v2_12_controllerthe other connections are for  other sensors already connected to the garden. some of these are shown below namely: sump tank float switch,  sump tank temperature sensor, ph sensor and a flow-rate sensor

fishtankSensors2the water is normally very clear, it looks brown because of dust particulate i dislodged when i dug the hole in the growbed. this will clear in a few hours. the smart control power socket for the fish tank pump, sump pump and lights is shown below:

powerStripthe v2 smart controller board also supports usb video. the camera for monitoring fish is show below

kj_v2_12_cameraso where is this 5000gal tank i was talking about … so where do these pipes at the end of the grow bed come or go to. one goes from the sump tank, one comes to irrigate the grow bed from the fish tank. this is show below

pvcto5000gand a picture of the fish tank

5000galyou can see the two pipes on the far right. by the power of gravity, i learned the hard way to make sure that i break siphons .. draining so much water onto the floor is frightening and not fun. my friend brent taught me once how to break these using an upside down one way flap valve, a lesson that has come handy many a times.

siphonControltank outlet and tank inlet

siphonReturn2i have experimented with different returns … i like using a venturi .. but i don’t like how they load the pumps nor siphoning issues. i also like to return splash as i learned from tom sepreno from s&s aqua farm. lots have been said about him. so a splash return for aeration is shown below

siphonReturnbig tanks are fun because you can have a floatation device, my underwater cam is also shown


the v2 controller graphs now show the grow bed level and tds increasing.

raisingGBone day later is show below.

raisingGB2i’ll get to more information about this shortly namely, electronics, software, how i build the diy  5000 gal fish tank, the growbeds i use etc