After a lot of searching I finally found a good schematic for a PH monitor. The author of the original schematic is richard.c from the electro-tech-online forums.

Because I didn’t want to play with chemicals and etch the board myself, I decided to order a PCB from a fab house. However, since there is no PCB design I had to recreate the schematic in Eagle and put together the PCB. So I sat down one day and within a couple of hours I had the schematic done in Eagle. There was a little error in the original schematic and I’m glad I spotted it before I ordered my PCB . After another hour or so I had the PCB layout ready as well. I used BatchPCB to order a prototype board as their prices are reasonable for low volume orders. The only thing is it takes about 6 weeks to get your PCBs back, but that’s fine with me.

So last Friday I got this in the mail:

I had ordered the parts from DigiKey in advance (see table below) so I sat down and started populating the board. The build is pretty straight forward, all through-hole parts and not too many of them:

I found a “bug” with U4, but at least it wasn’t fatal enough to render the boards useless. I had reversed VO and VI so all I had to do to fix it is mount the IC on the bottom. This is now fixed in the latest version.

So I connected my PH probe and calibrated the board using a 7pH fluid (turn RV2 until VPH reads about 1.709V) and then a 10pH fluid (turn RV1 until VPH reads about 2.441V). I have not connected the module to my arduino yet but that should be straight forward as well. Only trouble is I’m running out of space on my 16×2 LCD…

Eagle Project files: (includes board, schematic, gerb files and gerp process file)
http://joro.geodar.com/code/PH%20Amp%20eagle.zip

Note: I have not followed any design rules (because I don’t know them) for the PCB, only kept the analog and digital parts separate as per Richard’s advice.
BOM:

PH Amp BOM

FTS:

Rastas:

Nightmares:

Rainbow Pocillopora:

Meteor Shower:

Ricordea Florida:

It is quite popular to have some kind of fuge or sump connected to your aquarium so that you can keep the equipment out and grow some macro algae in there that both keeps the appearance of the tank simpler and keep the nutrient levels low. Best way is to drill the display tank (DT) and pipe it to the refugium/sump (fuge), however my tank is already setup so I didn’t want to take everything out just to drill it. So I decided to build my own hang on back fuge. The volume is about 5gallon and I can move all my equipment in it to keep the tank look simpler. Also I can grow some chaeto in there and add a skimmer.
So here is the initial plan:

I ordered some plexiglass and started bending, cutting and gluing:

Test fit:

Finished:

I added a single baffle for now just to have a small compartment that will act as external overflow and a big compartment that will actually hold the rock and algae:

Another test fit:

Then I had to do the skimmer box that sits in the DT:

Testing the hangs::

Drilled some 3/5″ holes and put everything together:

Little pipe from the pump in the small compartment:

Everything came out really good. I added 5lbs of LR, some chaeto and the sea lettuce algae that I had in my tank.

Now I have to do a top to reduce evaporation and make some kind of lights. More on that when the parts come