Time for another update! I've now got a reactor and a lot more circulation. I started with a small wavemaker (Fluval CP2), and attempted to construct a bypass to run the reactor from the filter. Unfortunately I found that even with the bypass, the flow from the filter dropped off quite a bit, and also my reactor leaks a little bit (it is only a cheap one). The leak isn't bad enough to negatively affect the performance of the reactor, but enough to make a puddle in the cabinet so I opted instead to mount the reactor inside the tank and power it from a separate small pump (NewaJet 1200). The end result is very effective in terms of flow, and although it's early days yet the reactor seems to work well. Although the wavemaker is theoretically powerful enough to achieve sufficient flow combined with the filter, at least in terms of numbers, it would have been difficult to eliminate all deadspots. Now with the addition of a separate pump for the reactor in addition to the wavemaker, there are definitively no deadspots anywhere.
The reactor, pump and wavemaker are all located at the end furthest from the filter, and the reactor has an outlet located at the top (water flows in at the top, down the reactor column, then up through a pipe in the centre of the reactor and back out), to which I have added an adjustable duckbill nozzle, allowing me to direct flow towards the front of the tank and slightly upwards to create some surface agitation. Meanwhile the wavemaker is located further down to create a gentle flow in the lower part of the tank, back across towards the filter. The reactor does gurgle a bit and the flow is surprisingly powerful, so I have opted to run the pump on the same timer as the CO2 solenoid so it doesn't run 24/7. This way the noise isn't constant (not that it's unbearable anyway) and the fish get a bit of a break from the currents (though I have been careful to make sure there are always some areas where the current is always very gentle as gouramis in particular don't like it too strong, and in general the fish seem quite happy with the setup now). Meanwhile I still have an airstone running when the CO2 is off so surface agitation is maintained.
Having changed the setup I've got to experiment with the injection rate again but so far things look promising. I'm happy with the way the setup is working, and the plants are definitely showing the benefits. One of the new plants I bought a few weeks ago has already doubled in size, and the smaller echinodorus towards the front has started producing runners, something I've never seen it do in the three years that I've had it. The large plant at the back on the left (I can't remember what it's called!), which has been there since day 1, I have pruned quite heavily as the growth it had wasn't particularly healthy. Now with the proper setup it should have a chance do put on some healthy growth.
...) just place it at each corner of your tank at the substrate level and look at the CO2 bubbles, do they rise up more or less vertically and only start moving 'sideways' nearer the surface? Or do the bubbles start moving 'sideways' near the substrate.