Failed Inline Heater and CO2 reactor

[peet]

Thought I'd post my failed diy inline heater and CO2 reactor project. The idea was to get the ugly heaters and CO2 reactor out of the tank and underneath where no one can see them. I constructed the reactors out of 100mm pvc and used uniseals to create the inlet and outlet fittings. Water was pumped into the first orange reactor from the bottom (image 1), travelling vertically past the two 300 watt heaters (heaters and lid shown image 2) and then into the co2 reactor where it was directed downwards to the bottom of the reactor and out to the cannister filter. A limewood airstone was put in the grey reactor slightly above the outlet (thin airline in image 3) the idea being that the downwards movement of the water suspends the upward movement of the bubbles allowing longer reaction time and therefore better absoption of the CO2 by the water.

Image 1

Image 2

Image 3

Heater Problem: Well plumbingwise the system seemed to work pretty good. I was a little bit nervous about leakage around the heaters as the fit with the uniseals was not very tight, but it worked and had I carried on with the system I would have come up with a way of wrapping the heaters with some kind of tape to increase their diameter. I plugged it all in and set it off BUT after 24hrs my tank was down to 22C down from 27C.. I started to worry about my Discus!! Due to the opaque pvc I was unable to see when my heaters were turning on and off, but everytime I did pull them out they were off and the water inside the reactor appeared to be very warm. I can only think that the flow through the reactor was too slow allowing the water inside the reactor to rapidly heat turning off the heater whilst the water in the tank remained cool. options to fix this might be to turn the heaters up to the highest they can go and then see whether the heaters will stay on for longer... or to increase the flow. Anyone else have any theories why this idea didnt work??

CO2 Reactor Problem: I pulled the heater reactor off the system and left the grey CO2 reactor, putting the heaters back into the tank. My ph vs kH tests show that my Co2 is 15 ppm max and the system has been runnign for about 3 weeks now. It would be lovely to have a clear perspex tube so I could see inside the reactor... but the cost would be to high. It sounds like the CO2 builds up inside the reactor during the day creating a void near the top as you can hear the water dropping down inside the reactor from the top... seems to be absorbed/escaped by morning as noise is gone.... How could I improve my absorption rate... planted tanks generally want something around the 30ppm??? Perhaps the reactor is too wide slowing the water flow too much and allowing bubbles to travel too quickly to the surface. The shop bought intank reactors are much narrower...... I am having a few algae issue (BBA, orange snot and spyro) and this is probably due to high light and ferts but co2 still being relatively low..... Your comments would be most appreciated

[Ira]

Turning the heaters up higher would be a pretty poor way of doing it. The best way is to have as much flow as possible over the heaters. You want the temperature of the water inside the heater chamber as close as possible to the overall tank temp. The lower the flow the further away it it can get. Problem is trying to put something that works best with high flow in series with something that works best with low(Or at least lower) flow

For the CO2, ideally you could put some kind of spiral to give the CO2 more contact time. I'm not sure how could do it easily with what you have though. Maybe if you want to stay with the PVC pipe you have just run it through a long coil of hose inside.

[Artem]

I think you're meant to put sponge or bio balls inside the PVC to trap the CO2 bubbles until they naturally absorb into the water. Maybe if you can have a diffuser connected inside the tube that would help with the CO2 dispersion

[alanmin4304]

I have a CO2 diffuser that looks similar and works well. Flow from filter is in the top and out the bottom and CO2 is in the bottom but airhose discharges at the top and is released straight from the hose with no diffuser. You may have restricted the flow with your pipe sizes. mine works well. CO2 is released at the top but is pushed down by filter flow.