Overview

Unfortunately I did not get to see the boxes that the reactor came in.  The reactor was purchased from a LFS and they inspected it prior to my picking it up.  The reactor itself came in a single box with all the tubes and instructions contained inside (fig 1).  The pump (a pan world unit) came in a separate styrofoam box.

  

Fig1.  The GEO 818 as supplied. The reactor body and Pan World Pump.	Fig2. The lid, showing white bolts and the union for the pump retun and pH probe socket

On seeing the reactor my first impression was that it was huge.  The name 818 refers to its dimensions.  8 inches in diameter and 18 inches tall.  On inspection of the unit it looks very nicely put together.  There are no glue spills, rough edges or acrylic burrs.  The lid is clamped down and the body contains all of the pipes and fittings (fig 2).  The pump is not attached.  One thing I immediately noticed was that the ports on the reactor were labeled with their function, such as CO2 inlet, feed, effluent.  This was a nice touch, simple, but extremely useful.  The main body is made from clear acrylic tubing sitting a black acrylic plate.  The pump feed connection is supplied prefitted to the body of the reactor with a uniseal.  The top is a black flange glued to the acrylic tube and the lid is a disk of clear acrylic fitted with a union (for the pump return) and a pH probe port (fig 2).  The lid is held down by 12 white plastic bolts that slot into the keyhole cut top plate.  Removing the plate involves turning each a few turn, twisting the lid slightly and removing. 

Assembly

The total assembly of the unit took approximately 30 minutes.  Step one, slacken the retaining nuts around the head of the unit and remove all of the pipes and paperwork.  The instructions for assembly are very poor, however the unit is very simple to assemble even without the help of detailed instructions.  After removal of the chamber contents it is clear that there are multiple hoses etc (fig 3). 

Fig 3.  reactor contents removed from the body	Fig 4.  The grey plugs need to be removed from the pump.

The first step was the assembly of the pump and its connections.  Each opening on the pump was capped with a grey plug.  These were removed and Teflon tape fitted to the screw thread (fig 4).  The two grey threaded elbow/pipe nipples were screwed to the intake and the return.  The alignment of the pump was determined by placing it on the base such that the pump baseplate lined with the holes in the black acrylic and the two fitting adjusted such that the outflow faced the reactor base and the prefitted connections there (fig 5).  With the pump in place, the distance between the two pipe nipples was measured and a piece of the plastic hose cut to size.  This was moistened and slid onto the reactor end first.  Holding it in place, the pump nipple was slid into the tube and fitted such that the pump sat over the holes (fig 6). 

 

Fig 5.  Alignment of the pump and reactor  feed prior to cutting and fitting claer pipe	Fig 6.  The clear pipe is fitted first to the  reactor, then to the pump and clamped  down using supplied fittings

The pump was then screwed down to the base plate using the four white plastic screws and washers (fig 7).  Peforming the assembly in this order saves undue stress on the reactor body.  The next step was the alignment of the pump intake to the reactor.  The top was placed back over the screws and the union at the top opened to allow the down pipe to rotate. The down pipe was slid around till it lined up over the pump intake and the distance between the pump and reactor nipples measured (fig 8). 

 

Fig 7. After fitting the lower tubing, the pump is affixed to the base with the 4 plastic screws	Fig 8.  The top is refitted, the union opened and the down pipe aligned with the pump intake to measure the length of pipe needed.

The hose was cut to size and slid first onto the pump intake then the reactor down pipe was released from the reactor by opening the union and then the nipple seated into the tube.  This prevents stressing the white plastic pump mount screws.  Once seated the union was checked and closed to make a tight seal.  The white plastic cable clips were placed around each nipple/pipe connection. Having fitted the pump, the reactor feed was assembled.  This is comprised of a length of clear plastic tubing with a black reducer at one end connected to a larger bore of pipe.  This latter piece of pipe allows the user to slide an MJ type powerhead into the end to act as a feed pump (I use an MJ400).  The connections between the two pipes are presealed with cable clips.  I personally found this to be a great feature of this product.  In the past I have assembled reactors only to hunt fittings to allow a connection to a feed pump.  The assembly of this required only the tightening of the prefitted white screw to the inlet premarked as feed.  The effluent was similarly fitted, and comes supplied with a flow regulator tap, again a nice feature (fig 9).  The CO2 feed includes a one way valve to prevent back pressure forcing water into the CO2 regulator. This is assembled as above into the CO2 labelled fitting.  While some reactors have self filling bubble chambers, I added some RODI water to the chamber prior to fitting the CO2 feed (fig 10).   

Fig 9.  Assembly of the effluent showing  the flow restrictor	Fig 10. Assembly of the CO2  feed showing the one way valve	Fig 11. The sponge foam insert is added and caribsea media used to fill to the line on the geo label.  The lid is refitted

Lastly, the union at the top was opened and the lid removed to fit the media chamber.  The reactor comes with two precut plastic mesh sheets.  These will prevent large media from falling through but I personally prefer using a smaller media.  Thus, I had to make a media trap out of foam.  While this was a simple task to perform (assuming you have the foam or filter pad) it would have been nice to have had this option included with the purchase, coupled with the poor instruction, this would be my main issue with this unit.  Once the foam was fitted, the two precut mesh sheets were slid down and the media added.  I used Caribsea crushed coral, the unit took 25-30 lbs to fill to the line at the GEO label  (fig 11).  The media was prewashed prior to adding.  The top flange was cleaned of media residue, the O ring checked for seating and the top fitted.  The screws need to be tightened in an alternating pattern to ensure seating and require just hand tightness for a seal.  The top union was closed and the reactor was ready.  The last step was the insertion of the pH probe.  The top of the reactor contains a port through which the probe is slid.  Once inside the nut is closed down, compressing an O ring onto the probe side and sealing the unit (fig 12).  In the past I have monitored the effluent for pH.  The inclusion of a port for the measuring of the reactor contents pH increases sensitivity of the unit and is an excellent feature of the reactor.   

Fig 12. The pH port is a nice addition

 

My previous experience with reactors and plumbing in general suggested a water test for leaks and this was performed.  The reactor was fed with a MJ400 unit using fresh RODI water.  As the water level rose the reactor was checked for leaks. Finding none, the reactor was filled till water exited the effluent pipe.  Knowing that the media would remain cloudy, I used separate buckets to feed water and collect water rather than recirculate so that the dust could be removed (fig 13).  After confirming the unit was leak free the recirculating pump was turned on.  Immediately bubbles churned through the system and then settled.  My impression was that the pump was very quiet.  The water inside the reactor became quite cloudy from the churned bubbles and the media dust.  I also noticed that bubbles were drawn in through the bubble trap/CO2 feed.  This was remedied by blocking the free end of the black CO2 pipe.  After running for several minutes the CO2 feed was connected to the solenoid of the CO2 regulator/tank, the feed pump placed in the sump and the return pipe cable tied to the side of the sump to prevent it moving and the unit allowed to run. While the instructions for assembly may be lacking, the instructions for dialing the unit in are well written and explained and as such, I will not repeat them here.  My system uses a Milwaukee sm122 pH monitor connected to the solenoid of a 20lb CO2 bottle and regulator (fig 14).  The initial flow through the unit is in the range of 3 litres per hour.  This leads to intermittent switching on of the CO2 every 5-10 minutes or so.  Satisfied that the unit is running, I left it and just checked for leaks every couple of hours.  After 24hrs I performed a Calcium and an Alkalinity check on the effluent.  10 mls of the effluent was collected and added to 90 mls fresh RODI water.  Salifert test kits were used.  Correcting for the 10f old dilution factor, the dKH of the effluent was around 30 and the Calcium level around 900-1000.  Over the next few days I will slowly dial the unit in to keep my tank parameters at a steady state. 

Fig 13. The Reactor is flushed to remove  residual dust prior to final installation	Fig 14. The reactor installed and  connected to CO2 and pH controller.

Overall

This is a very nice looking and extremely efficient unit.  The pump is silent and the fact that all of the pipes/ valves/ plumbing are supplied makes this unit extremely attractive.  The tapid assembly and ease of use are also a plus.  On a down side, it would be nicer to have larger heads on the white fittings at the lid, opening and closing them is somewhat fiddly, but not sufficiently difficult to make me change them myself.  The fact they will only be opened and closed every 6mo or so makes them OK.  The lack of a sponge for smaller filter media was a surprise as all other fittings are supplied.  Another improvement that could be made would be more specific instructions on the actual assembly. 

Marks out of 10

A solid 9.0   Adding a sponge and better instructions would bring this unit very close to a 10. 

Great value for money, nicely built and very robust.