CoralDanimal
Active Member
- Joined
- Apr 19, 2017
- Messages
- 304
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- 313
- Location
- Bay Area
- What state or country do you live in
- California
I've read Randy's article on ORP - http://www.reefkeeping.com/issues/2003-12/rhf/feature/ - (which is great by the way) and I understand ORP is not a first class citizen in the measurement world unless you're putting ozone in the tank. At best, it's useful for broader tank trend detection. My ORP has been going down recently, which is why I'm concerned.
My tank is fairly small (Red Sea Reefer Nano -> ~30 gallon system). For first 6 months, the tank was always in the high 300s or low 400s for ORP. When it would drift down to the mid 300s, I took that as a sign for a water change. Although the water change would drop ORP at first, it would rebound to higher levels than it was pre-water change. About two months ago, my ORP started a downward trend. Mid 300s -> low 300s -> 300. I have a fairly standard bioload (2 clowns, 1 captive bred mandarin (don't worry, he's eating prepared foods), 1 cleaner shrimp) and all parties are accounted for so I know it's not from die-off (unless I'm missing something obvious). There are only two changes to the tank I've made in that timeframe:
1. Although my captive bred Mandarin eats prepared foods and is nice and plump, I want to have as big of a pod population as possible. I replaced my oversized skimmer (Eshopps X-120 Axium w/ co2 scrubber reactor for air intake) with the Tunze 9004 which fits in the overflow compartment of my sump and turned the rest of my sump into a large refugium powered by a Kessil H380 grow light. The chaeto growth has been insane since making this change and has required weekly culling (which I bundle up and put in the display tank for the Mandarin to peruse). I run the Kessil refugium light on a reverse photo period and it's so strong that it actually pulls my pH up during the night to 8.1 from 8.0 (where my pH is at after my day lights turn off). No surprise the ORP falls as the pH goes up which is one of the relationships discussed in Randy's article. Does all the photosynthesis in the sump with crazy chaeto growth have an effect on the ORP? In addition to creating a pod haven, algae in the display tank has been declining nicely.
2. For many months, I had been doing 10% water changes every week or every other week. After a calcium mishap (I dose two part and the calcium was drawing air for weeks which made kH rise and calcium drop to 320), I did a number of a larger water changes to try and correct that imbalance. 25% water change weekly for 4 weeks in a row. Calcium/kH levels are getting back to balance (390 calcium, 7 dkH). I always mix to 1.025, raise to exact tank temp 78 degrees F, and let mix for about an afternoon before the water change. Is this somehow affecting my tank (and indirectly ORP) negatively? I was concerned maybe the changes are too large and I might set my tank into re-cycling.
Maybe I'm being overly paranoid and I should just look at the coral health and other probes (pH, salinity) and test kits (nitrate, calcium, dKH, phosphate) instead of letting ORP make me second guess my tank's stability. Any thoughts would be appreciated.
My tank is fairly small (Red Sea Reefer Nano -> ~30 gallon system). For first 6 months, the tank was always in the high 300s or low 400s for ORP. When it would drift down to the mid 300s, I took that as a sign for a water change. Although the water change would drop ORP at first, it would rebound to higher levels than it was pre-water change. About two months ago, my ORP started a downward trend. Mid 300s -> low 300s -> 300. I have a fairly standard bioload (2 clowns, 1 captive bred mandarin (don't worry, he's eating prepared foods), 1 cleaner shrimp) and all parties are accounted for so I know it's not from die-off (unless I'm missing something obvious). There are only two changes to the tank I've made in that timeframe:
1. Although my captive bred Mandarin eats prepared foods and is nice and plump, I want to have as big of a pod population as possible. I replaced my oversized skimmer (Eshopps X-120 Axium w/ co2 scrubber reactor for air intake) with the Tunze 9004 which fits in the overflow compartment of my sump and turned the rest of my sump into a large refugium powered by a Kessil H380 grow light. The chaeto growth has been insane since making this change and has required weekly culling (which I bundle up and put in the display tank for the Mandarin to peruse). I run the Kessil refugium light on a reverse photo period and it's so strong that it actually pulls my pH up during the night to 8.1 from 8.0 (where my pH is at after my day lights turn off). No surprise the ORP falls as the pH goes up which is one of the relationships discussed in Randy's article. Does all the photosynthesis in the sump with crazy chaeto growth have an effect on the ORP? In addition to creating a pod haven, algae in the display tank has been declining nicely.
2. For many months, I had been doing 10% water changes every week or every other week. After a calcium mishap (I dose two part and the calcium was drawing air for weeks which made kH rise and calcium drop to 320), I did a number of a larger water changes to try and correct that imbalance. 25% water change weekly for 4 weeks in a row. Calcium/kH levels are getting back to balance (390 calcium, 7 dkH). I always mix to 1.025, raise to exact tank temp 78 degrees F, and let mix for about an afternoon before the water change. Is this somehow affecting my tank (and indirectly ORP) negatively? I was concerned maybe the changes are too large and I might set my tank into re-cycling.
Maybe I'm being overly paranoid and I should just look at the coral health and other probes (pH, salinity) and test kits (nitrate, calcium, dKH, phosphate) instead of letting ORP make me second guess my tank's stability. Any thoughts would be appreciated.
