Help with RO on 500g trickle changer

[NetMax]

Designing a 350g Discus habitat (500g with sump). Using an inline feed to the sump of about 15ml/min. through RO filtration (5g/day). The system is massively biologically filtered, nitrification and denitrification, and uses mineral trays to re-mineralise. The sump uses a standpipe drain to home's drain piping. I've read the RO Basics and came away with 3 questions.

1) My tap water is low TDS & <1ppm chloramine, so I'm not using a DI stage. It would seem logical to go with 4 stages using 6 cans. Two catalyzed carbon (unbind chloramine and remove chlorine), one zeolite (remove unbound ammonia), two sediment filters (stage down) and the RO membrane. However I don't see this configuration used.

2) I'm unfamiliar with filter cans. Is it impractical to use loose minerals (carbon & zeolite)?

3) I want to constrict the flow at the filter system's input to 15-20ml. Logically, the pressure will still build to municipal pressure at the RO as the membrane clogs, as pressure is a function of resistance (doesn't require much flow), Basically this would keep the system below municipal water pressure and restricted to 15-20ml/min in the event of a failure. However I'm uncertain if this will mess up the bypass valve for the waste water separation.

My first post, hope it was ok. Thanks in advance!

[danotaylor]

Welcome to SD mate.
Seems to be a very complicated system, above my pay grade.
What are your goals as far as fish goes? Guessing display given the tank size.
What about decor and scaping? Bare bottom, hard scape, planted, unplanted?
I will say the term “massively biological” is a misnomer.
Biological filtration is living. The presence of massive amounts of media will never cause more “biological filtration”. The amount of bio filtration is determined by available bioload. Bacteria is living and requires food, the colony can never outgrow its food source. The size of your bacterial colony will be determined by your stock density & feeding regime. It’s important to have adequate media for the colony size but having tons serves no real purpose.
Looking forward to hearing more

[NetMax]

Thanks for the welcome! Display tank (wall unit), 15' long x 26"high x 20" deep with two 7' 65g sumps. More accurate to say massive surface area & habitat for microbiome (in case my 10% water change target was questioned). Almost blackwater, planted, driftwood, inert coarse sand, sculpted polystyrene background with caves & plant pockets. Goals are to start with a small colony of Discus (7 or 9), and let them grow & breed for a few years. When their offspring are numerous and large enough, I'll take the tank out of breeding mode and continue the stocking with tetra dither and bottom feeders. By then the tank will be 100% planted (no substrate visible) and the dither and bottom feeders can go through their spawning cycles with some success. Tank will be quite low maintenance, so I'd like to get this RO set up & tuned right. My long term goal is for most of my efforts to go into daily food prep and gardening every 2-3 weeks. The purpose to having 'massive' media capacity in sponges is that around 2 sq.ft/g, detritus dissolves faster than it can accumulate, which makes it maintenance-free, but you have to be fully planted and stay on a continuous water change (which gets tuned upward as bioload increases). In practice, the 1st stage sponges do get cleaned every 4-5 years as scales, teeth, sand etc don't dissolve very well, but you get the idea.

[jwcarlson]

Can't comment on the guts of an RO system, really, but why so little? 1% water change per day with no physical debris removal? Or are you planning on this in addition to other cleaning/water change? Sounds like a cool setup, though!

[NetMax]

Can't comment on the guts of an RO system, really, but why so little? 1% water change per day with no physical debris removal? Or are you planning on this in addition to other cleaning/water change? Sounds like a cool setup, though!

Correct, I'll start at 10%/week which will be plenty for the low initial bioload. Nine Discus are <1kG of metabolic mass producing about 5ml of ammonia per day - from my research). I'm hopeful that within 6 months, it'll be net-zero for NO3, At the other extreme, I kept my fish room sales tanks on a 20% water change every 4.5 hours, 24/7 for close to 100%/day. I try to let the science guide me. For debris removal, I'm using a 2" perforated drain pipe along the tank bottom front for 90% of my sump intake, as this water will be the least oxygenated and detritus will roll down to it from the nozzle return orientation. The pipe will be SS mesh guarded and 3,000gph over 13' will be a relatively slow water movement. The trick will be to get the water to flow 'up' into the weir to breach the drain standpipes at the right rate (so I have 6' of 2" adjustable pipe as a skimmer, in case I got the science wrong).

Perhaps my 1st post should have been an introduction instead of a question on RO? What formats does this site accept for pictures, pdf, wmf, dxf or just jpg? My drawings are more descriptive than I can write. Thanks.

[Vanman]

We need pictures of this. Welcome to SD.

[danotaylor]

If you take a picture of your drawings on your smart phone you can load jpg. directly from your phone

[NetMax]

If you take a picture of your drawings on your smart phone you can load jpg. directly from your phone

Did a pdf print & translate to jpg which seems to have worked fine, thanks.

We need pictures of this. Welcome to SD.

Thank you.