What are the cost differences between doing a 100 gallon water change weekly on a marine tank vs a Fw tank using tap water?
What about the time involved?
Can you just dump the salt in while the tank is refilling?
DOC's are not the issue, they build up and then level off.
If you are using good testing methods and feel that is easier and you can test all the parameters(NO3/PO4/Ca/Mg namely) and it will cost you less $ and save you time, sure. Why not?
However, I measured the time it took for me to do a simple 50% water change, the amount of dirt and muck removed, the differences in redox levels/O2 levels, the ease of cleaning the glass when it's 1/2 full, the time it takes for me to change filters/clean filters, CO2, tidy up etc while the tank is refilling etc..........none of which I can do while I use test kits.
So I spend much less time and have a clearer, cleaner tank and I do not have to play chemistry merely to monitor the tank
If I really want to "learn", I use the test kits to answer a purpose driven question(say, does 30ppm of NO3 cause algae independent of other parameters??), not added work and long term monitoring.
FOLKS HAVE DONE NO WATER CHANGES for well over a decade, I kmnow Dave did none for 2 solid years, so did a client with discus etc.
The trade off is: is it easier and cheaper. for marine critters worth a lot of $, perhaps, still for a nano reef, remove the skimmer and all the high tech stuff, the simple 50% water change once a week on a 30 gallon tank is worth every penny for the 15 gallon of salt mix. 3000 gallon tank?
Then it's more likely to do the monitoring.
When folks compare FW systems, they often suggest that it takes then too long to do a WC, this is baloney hyperbole excuse.
Even a hillbilly like myself can figure out how to drain and fill water without using a bucket
You use a hose or a little giant pump sump to pump water out of the tank and to refill using the tap/RO etc, water never touches the floors(Gee, clients really do not like that!) nor does it take long.
Some folks suggest/argue it's faster/easier to do the testing, well, I'm not sitting there testing while the water is draining and filling! I'm cleaning the tank.
Takes me 2 hours a week to do a 50-80% water change on a 300 gallon tank.
I go to the bathroom, I eat, I prune the 8x2ft footprint layout, I feed the fish, I change the Ehiem canister filters, I clean the sponge filters, I wipe the entire glass, I net out any muck, I fluff the organic matter out of the sediments, I rearrange things, I add a new CO2 gas tank, I dose the fertilizers, I talk to the clients.
I got lots of time while things refill, none which I can do if I have to sit and test.
Ever try and clean the back corners of a tank in a 24-48" deep tank? Not unless you have a snorkel or scuba
Why drag all that test kit or have a client pay for it and have calibration solutions etc all over? Water change is simple, effective and cost less and takes less time.
It takes very little skill or expertise to tell someone how to do it.
Try that with explaining how to make a claibration solution as well as why they should?
It's just far simpler.
Now say you still do not like water changes...........well, use the brain, not an excuse............set up a techy automated or semi automated water changes(turn a valve to drain, turn another to refill). AWC's use a solenoid, just like CO2 to drain when open slowly.
Then a float switch replaces water slowly.
Some folks do over flow drain and constant drips for refill.
We do this at the lab.
Then no testing and no water changes and you can have high growth/dosing without any issues etc.
Use your head to avoid work you do not have to do. :idea:
No need to accept the barriers imposed by others who really have not bothered to think things through.
In a 10 acre lake, you cannot really do a water change/manipulate the system and test kits where used in science to investigate things.
In our tanks using FW, it's easy.
Monterey Bay Aquarium has an open system, they can use the water right there and it makes things much easier for them.
Waikiki Aquarium cannot(even though they are right on the ocean, they cannot take water in there) and must make their's.
If you have a easier method, use it!
Do not place barriers in your way.
Keeping a nice algae free plant tank is not all science, it's basic hands on in the tank work, pruning, cleaning and staying on top of things and consistent.
It's horticulture, not nature.
I will say that it can be done(no water changes and using test kits) and I've done many years ago in our group. We found the tank did much better with at least 25-50% weekly water changes. Even the pickiest of scapers have said this(CAU, David Oliver, ADG, Amano, Myself, a number of Dutch in the NBAT etc).
It's more of a maintenace, keeping the tank clean and easier to work on it when it's lower. Who is going to buy 5-10 test kits and calibrate everything and micromanage? That's a hard pill to swallow for a newbie or even someone who's done the hobby for sometime.
You can do it for awhile, but most don't after a few weeks, months, ..years...... etc.
They use the plants and then stop and then mess something up and have to redo things or get a bad algae outbreak etc. So do folks that slack on their water changes.
We all slack off no matter which method, but the water change set up correctly can be the easiest way to manage that.