another update... I just finished replacing all of the 1/2" valves and 5/8" hose in my filter 'loop' with 3/4" hose, 3/4" full bore ball valves, and 3/4" fittings. The flow through the Rainbow Lifegard filter modules has now increased to more than 250gph, and the water level in my AquaTech post-filter increased to the same level that filter normally operates at when using its own built-in pump in a stand-alone mode. I never realized just how much of an effect that even 'minor' plumbing restrictions can have on overall pump and filter performance -after changing to all 3/4" plumbing the filter 'loop' flow rate is now exactly where it needs to be.
During the plumbing change I also discovered that one of my original 1/2" pipe fittings which was sold to me locally as supposedly being stainless steel was actually just plated steel ... and had already begun to corrode from the inside. All of my new 3/4" fittings are either PVC
or Polypro, including the hose barbs, so now there's zero risk of metal leaching/corrosion causing potential problems with the tank water.
Going to 3/4" plumbing with my existing mag 7 pump was a much better and far less expensive option than increasing the pump size to a mag 9 but keeping my original plumbing would have been. My immersed mag 7 pump already occupies a good sized chunk of tank real estate and already generates a good bit of water heating - the physically larger and more powerful mag 9 pump would have aggravated both of these issues besides costing another $70 or so.
I also popped open the Rainbow Lifegard modules to check build-ups. The pleated paper filter in the 'mechanical' module had just a bit of discoloration and no build-up, so I rinsed it and put it back in service. The initial charge of activated carbon in the 'chemical' module had loaded up pretty good (and was also starting to create back pressure on the gage), so I opted to postpone a switch to bio-media for the future and put in another new carbon charge (I'm not sure what the carbon is grabbing, but it's obviously grabbing something - right now at least). The UV
module showed just a tiny trace of build-up on the quartz tube which cleaned off immediately with one sponge wipe. The bio-balls in the heater module showed a small trace of surface 'slime' indicating that a bacteria colony is taking hold.
Up in the AquaTech post-filter the 1 u Rena filter pads have a bit more gray-black surface coating but weren't restricting flow so I left them in. If anything the super fine carbon powder which is escaping from the 'chemical' filter module but being grabbed by the the Rena 1 u filter pads seems to be improving their filtration ability based on the optical clarity of the tank water - probably by the same principle as a DE precoat with a sand filter. This unexpected development falls into the 'fortunate accident' category, but appears to be working great so far.
Water conditions appear pretty stable now that the cycle 'spike' has passed, and the Penguin filter's bio-wheels now have a noticeable bacteria colony going (as indicated by the color change), so after a 20% water change and putting in the fresh load of activated carbon I decided to stock up my new 55 gal
tank - which now has four 4" tinfoil barbs, a couple of 4" Parrot fish, and a 4" black pleco. We'll see how things go from here on out with the filter system now having some significant 'load' to deal with.
I've got some zeolite standing by for the AquaTech post-filter's media baskets just in case the bio-filtering can't keep up with the abrupt increase in NH3
now generated, but hopefully the Penguin filter's bio-wheels will handle it just fine with no need for a temporary zeolite assist (opinion based on how well the bio-wheel has worked in my sometimes massively overstocked 6 gal
Even though running a submersible pump and separate filter modules is a bit more expensive way to go versus using a canister filter with built-in pump, and even though a submersible pump takes up a bit of tank space, to me it's worth every extra penny to never have to deal with canister filter priming problems or air burps or pump noise again (you can probably tell by now that I've wrestled with a Rena XP2 canister filter on a previous tank setup - that's where the 1 u filter pads came from). With the submerged mag 7 pump feeding the Rainbow Lifegard modules on this new setup, it's a tremendous pleasure to just hit the switch - the pump self-primes instantly, it force fills all the modules with tank water, it forces out all the trapped air in less than 60 seconds without any bleeding, and after that everything runs totally silent (well, providing my tank water level is maintained above the Penguin filter and AquaTech post-filter spillways anyhow, otherwise they splash). It's also very reassuring to know that when the power fails while I'm away from home that my filter system will definitely restart OK on its own once power comes back on.