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timvdb · 12/26/2008, 05:04 PM

Hi Randy,

I have read your article on ORP with great interest and have a follow up question:

I have negative ORP readings on both my RODI water and reeftank water.

Background:
- 55l nanotank with lots of LR, 3 inch sandbed, a couple of a. percula, 1 c. poterri, 1 p. hepatus (i know, tank is WAY too small, but bugger is only 1 inch and will move to bigger meadows soon), 1 anemone, acropora sp., montipora sp., millepora sp., seriatopora histrix, discosoma sp., ricordea floridae, clavularia viridis, xenia sp., euphillia sp., zoanthus sp., 2 mitrax, 2 red hermits and 4 lysmata, bhergia v., various snails and polychaeta;
- 15l weir with growing c. racemosa and c. taxifolia, liverock, miracle mud, various sp. of copepods at 200lph water circulation;
- AquaMedic TurboFlotor Blue 1000 Skimmer skimming ok;
- Filtration with mousse and 1L Siporex (full of life) at 600lph;
- AquaMedic wave maker with 3 Hydor Koralia at 900lph each;
- I use RODI water and H2Ocean salt at 35ppt;

Tank readings are fine:
pH: 8.1
KH: 6.4 dKH
NH4+/NO2~0ppm
NO3<10ppm
Ca: 430ppm
Mg: 1340ppm
BUT my ORP reads at a NEGATIVE 185mV. I use HM digital's ORP-200 meter.

Also, my RODI ORP reads at -90mV even after 24 hours of heavy oxygenation. I read Randy's article and understand that ORP issues are complex. We should however expect ORP readings of +200mV for pH7 water and would like to expect a reading of +350-400mV for a reeftank.

I am quite surprised by my reading, which has however been consistent over the past couple of months and is troubling me.

All the inhabitants of the tank seem happy, but can someone please help me throw some light on the issue? And suggest a solutions (that preferably does not use O3).

Thanks a lot.

12/26/2008, 05:04 PM	#14
timvdb Registered Member Join Date: Oct 2008 Posts: 63	Hi Randy, I have read your article on ORP with great interest and have a follow up question: I have negative ORP readings on both my RODI water and reeftank water. Background: - 55l nanotank with lots of LR, 3 inch sandbed, a couple of a. percula, 1 c. poterri, 1 p. hepatus (i know, tank is WAY too small, but bugger is only 1 inch and will move to bigger meadows soon), 1 anemone, acropora sp., montipora sp., millepora sp., seriatopora histrix, discosoma sp., ricordea floridae, clavularia viridis, xenia sp., euphillia sp., zoanthus sp., 2 mitrax, 2 red hermits and 4 lysmata, bhergia v., various snails and polychaeta; - 15l weir with growing c. racemosa and c. taxifolia, liverock, miracle mud, various sp. of copepods at 200lph water circulation; - AquaMedic TurboFlotor Blue 1000 Skimmer skimming ok; - Filtration with mousse and 1L Siporex (full of life) at 600lph; - AquaMedic wave maker with 3 Hydor Koralia at 900lph each; - I use RODI water and H2Ocean salt at 35ppt; Tank readings are fine: pH: 8.1 KH: 6.4 dKH NH4+/NO2~0ppm NO3<10ppm Ca: 430ppm Mg: 1340ppm BUT my ORP reads at a NEGATIVE 185mV. I use HM digital's ORP-200 meter. Also, my RODI ORP reads at -90mV even after 24 hours of heavy oxygenation. I read Randy's article and understand that ORP issues are complex. We should however expect ORP readings of +200mV for pH7 water and would like to expect a reading of +350-400mV for a reeftank. I am quite surprised by my reading, which has however been consistent over the past couple of months and is troubling me. All the inhabitants of the tank seem happy, but can someone please help me throw some light on the issue? And suggest a solutions (that preferably does not use O3). Thanks a lot.