My set-up is well into the 1K gallons easy.
IMO, it is not about the price of the system, it is about the quality of filter cartridges, membranes, and DI resin they come with or you buy to reload them. And yes, that does or can effect the price of the system IF they indeed do come with the high end internals. But the cheapest system with enough canisters can be later loaded with the better innards. My set-up is an example of how that can be done, I got the hardware for $5 in a garage sale then loaded it wisely.
What does not read in the meters is the non electrical conducting substances in the water. When the electrical conducting substances get below a value the meter can measure it will read 000, and this is only a relative number of which this device is the best we have for a reasonable cost. What is so wonderful about all this is it does however give us a useful and reasonable value to share and compare from reef set-up to reef set-up, and a consistent
enough reference standard with which to watch for evaluation of our RODI system's performance.
IMO, once you get to 000 conductivity, yes there is a difference but the difference is splitting hairs far beyond the scope required. I say conductivity because that is actually what the meter is measuring, then it is calculated for a TDS value before it is posted to the LED display. I have to assume that if the substances which conduct electricity have been removed to a point about 185 times less than it was in my case, then the other substances must be responding to similar reductions. The greatness is that I have this TDS meter method to know my water is (again in my case) at least 185 times more pure than it was out of my tap. (185ppt / 1ppt is 185 times as pure. Thus my statement of 000 being at least 185 times as pure.)
Less we forget pure water will not conduct electricity at room temperature, it is the impurities in the water that provide an electron path for conductivity of which the TDS meter can then give a reading. The TDS meter is a great
reference tool!
So therefore to be pure I revise my statement:
In my opinion, 000 TDS is 000 TDS within the reasonable tolerances and scope of this hobby. It seems to me, we have impurities and substances entering our reef tanks via the air, off our tools, in our dose compounds, in the frozen foods, and no telling where else in volumes which dwarf the amounts of variations in RODI systems reading 000 with a properly working TDS meter. Do you agree?
I love this hobby, and I love having this forum for healthy discussions to learn from each other, don't you? This is good stuff and is good for the hobby.
LOL, I read somewhere, I forget where, where a person was wondering what had happened to the TDS reading of his water. All he did was add the salt mix to the proper salinity and his TDS reading was seriously bad. He simply didn't understand or hadn't been told that salt makes water conduct electricity to the nth degree. He thought his water had been contaminated somehow because his TDS meter read high. This is why I like to take the opportunity to once and a while explain the conductivity and TDS meter theory in a simple way, so new comers will realize we are not actually measuring impurities but are measuring how impurities effect conductivity.
Now, if someone would be so kind as to provide information showing how the differences in non conductive substances passed by less expensive membranes and DI resins, while a TDS meter in good working condition is reading 000, is a serious concern in a reef tank I would absolutley love to hear and learn about that. I am sure other reefers would want to know about that too. Frankly, all I have to go by is the relative assumption.
