ORP and Bacteria

[eagle]

Hey Randy, I have read your ozone article several times. Just wanted to see what you thought about some parameters I've been experimenting with. I recently moved my 75 gal tank in preparation for a larger tank I'm having built and fish room renovations. I decided when moving the tank to go bare bottom. For 20 yrs I've held onto the sand beds and refugium but after seeing how nasty the sand was I decided while breaking the system down to remove the refugium too. It was a nasty job. We were pretty shocked at just how nasty everything really was. I did a 80% water change with the move. I made the refugium an isolated skimmer compartment. I added a recirculating biopellet reactor made by reef dynamics and the recommended amount of ecobak biopellets and running 50 gph through the reactor. I have the effluent from the reactor running directly to the skimmer suction. When I got everything back up and going the only water the skimmer compartment was getting was from the biopellet reactor running directly thru the skimmer first. 50 gph. My ORP on Apex steadily climbed up to 450 range. I was scratching my head a bit. Years ago I ran ozone to try and reach 450. I checked the probes. But the tank is spotless. The sump is spotless so I figure it's just the absence of nutrients and large water change etc. All test readings are undetectable. 0.0 on hanna for phosphates. After a week of biopellets running I added a separate feed pump to the skimmer compartment. I figured I needed more water going to the compartment than 50 gph for my skimmer to process. When I turned the feed pump on (150gph) I noticed my ORP started slowly dropping in the tank. It dropped below 400. I turned the feed pump off and ORP stopped it's decline and slowly climbs back up to 450 range. So I'm assuming this is from the skimmer not processing all of the bacteria from the biopellets and more bacteria is being introduced to the tank when I upped the flow to the compartment. If this is correct, and I know ORP is very complicated, but could it be used to anticipate bacterial overpopulation. I know there is the BART-HAB test for checking bacterial populations. FYI the tank is very lightly stocked and I have an oversized skimmer. With the exact same equipment and sand bed/refugium my orp ran much lower. 250-300 range. It has been very interesting. The isolated compartment makes it pretty easy to see how effective the skimmer is working with different flow rates running to it. I'm just curious if the orp decline is bacteria being introduced into the water column or the skimmer not removing organics as efficiently with more flow to the compartment.

 

[Randy Holmes-Farley]

Interesting that the ORP was so high with the new setup.

My expectation is that the ORP in the biopellet reactor is lower than the tank, and increasing the flow through the reactor (is that what you did?) brings more of this lower ORP water to the main tank.

The bacteria are going to form a film on the pellets, and under this film, ORP will be pretty low. As stuff diffuses out of that underlayer, it will lower ORP in the water column.

I wouldn't assume that the ORP lowering is from whole bacteria (although that may be part of it).

ORP itself is a measure of a few selective redox active metals in the tank. Those may be a bellweather for other redox processes happening, but a skimmer may not impact the metals directly. So if, say, a bunch of ferrous iron is made on the pellet surface and it leaks out into the tank, the ORP declines, and a skimmer won't remove all such ferrous iron (but it may remove some if the iron is bound to organics that are skimmable).

Increasing the flow from the pellets to the tank overall may bring down tank ORP a bit. I wouldn't assume that is a problem, and I also would not necessarily assume that ORP is tracking with bacteria remaining in the water column, although it may to some extent.

 

[eagle]

The flow through the reactor has remained the same at 50 gph, but I added a small pump to feed more water to the skimmer. So less contact time with the biopellet effluent and the skimmer I'm thinking. Maybe more of the biopellet material is making its way into the system before running through the skimmer again. I tried biopellets a year ago with the sand bed and had a bad bacterial bloom. After that experience I put the reactor away. After researching some successful biopellet tanks more I've been leaning in the bare bottom direction. And I'm trying to safeguard against another bacterial bloom (white gunk) or any other of the biopellet pitfalls. I anticipate having to slow the flow through the reactor eventually. So I added a small pump just to feed more water to the skimmer compartment. I actually set up a little orp control via Apex on the feed pump last night and had it switch off at 450 then back on at 440. I'm still nervous about having any bacteria get into the system. But then too I see the zeovit systems where they introduce the mulm into the tank. It's a bit of an experiment it seems at this stage. Nobody seems to know if it's bad or good to let bacteria into the water. I read an article by Richard Harker that bacteria populations in our tanks were much higher than in the natural reefs.

 

[eagle]

My bad biopellet experience was with the reactor effluent pointed at the skimmer suction in the middle of my sump. In a much dirtier tank. Levels weren't super high but it was a constant battle to keep them low. A lot of the biopellet effluent was making its way into the tank. I didn't have my apex then either to see parameters. That's why I wanted to separate the compartments this time and tie the biopellet effluent directly to the skimmer suction. With it being in its own compartment it gets run through the skimmer a couple times before going back into the tank. I have a lot more control over it.

 

[eagle]

Visual. Skimmer compartment on right isolated from system and fed via biopellet reactor and small pump.

 

[Randy Holmes-Farley]

FWIW, my main reason for dosing vinegar, aside from reducing nutrients, is to get more bacteria into the water to feed filter feeders.

I wouldn't conclude that reefs have excess bacteria.

This study suggests skimmed reef tanks have a lot less than natural seawater:

Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration ? Advanced Aquarist | Aquarist Magazine and Blog

 

[eagle]

Thanks for that link. Here's the one I read. http://www.fishchannel.com/saltwater-aquariums/aquarium-frontiers/testing-for-bacteria.aspx

 

[Randy Holmes-Farley]

Thanks for that link. Here's the one I read. Testing for Bacteria in the Reef Tank

Thanks.

That test detects the ability to consume methylene blue, which not all bacteria can do. I personally would not use such a test without some validation since I assume there are many species it doesn't count, while the Feldman article actually counts bacteria bodies.

Richard's article is also pretty old now, coming out in 2001. That doesn't mean it is wrong, but it does reflect old technology.

 

[eagle]

I agree. That was quite thorough. I've been reading it since u posted lol. Interesting the bacteria population in plastic containers. I just started an auto water change after reading your math on water changes. I used to think it would waste new salt water but after reading your article I decided to try the daily water changes via 2 litermeter pumps. Wish I'd done it years ago. I wonder what adding a small amount of bacteria in your water barrels would do when doing non stop water changes. Thanks again for the link. Lot of information there.

 

[Randy Holmes-Farley]

I agree. That was quite thorough. I've been reading it since u posted lol. Interesting the bacteria population in plastic containers. I just started an auto water change after reading your math on water changes. I used to think it would waste new salt water but after reading your article I decided to try the daily water changes via 2 litermeter pumps. Wish I'd done it years ago. I wonder what adding a small amount of bacteria in your water barrels would do when doing non stop water changes. Thanks again for the link. Lot of information there.

I'm glad it was useful!

How would you add bacteria that way?

 

[eagle]

My take from the article as a whole was reef tanks have less bacterial population than the ocean. So more bacteria would be better? My take from the latter section of the article was the bacteria population in freshly made IO water in their plastic container was bacteria rich. When doing a 17% water change the bacterial population rose sharply in the tank. Those were plastic containers that had tank water in them before. My initial reaction was this is another reason to do frequent water changes. I have new barrels. Would it be good to seed them with some beneficial bacteria? So when doing water changes its adding more beneficial bacteria to the tank?

 

[Randy Holmes-Farley]

Used tank water will have a lot of bacteria, but I'm not convinced that making up new salt water will have more bacteria than the equivalent amount of tank water that it might displace, and the species there may not be the ones that will thrive in an aquarium. The data in the article show a lot less bacteria in the new salt water than in the tank water. Yes, it is a source, but it does not add net bodies of bacteria during a water change.

Also, Reef Crystals is an unusual mix and possibly not the best indicator of what may happen with other mixes which do not contain organics that the bacteria can feed on (RC does).

 

[eagle]

There was a 7% increase as well with regular IO on day 3 water change. I will experiment with this. I use IO. I will be watching all parameters closely as the biopellets kick in more. There are many variables. Good bacteria vs bad bacteria etc. The bacteria growth in the water change vessels was just one more variable I never thought of. I will continue to skim the effluent from the biopellet reactor. I don't want any blooms or cyano. I'd be interested in which bacteria are easily skimmed and which arent. Maybe it isn't certain types just the amounts in one area that the skimmer can pull out.

 

[Randy Holmes-Farley]

Adding a salt mix may provide trace elements (such as iron) that bacteria need to grow rapidly. That can be good, or bad, if the bacteria in question is cyano.

 

[eagle]

No. I use regular IO and always have. Not changing that. The whole cyano thing is something I want to avoid. I'm an engineer so I love to tinker and over think stuff lol. I'm all over the world most of the time and never home. So I really have to automate things as much as I can and make things super simple for others to look over the tank. I believe in water changes for stability. And the bacteria growth in water change vessels perked my ears up.
On another non reef topic but orp related. If you wanted to dose chlorine to a swimming pool, what ORP would you shoot for. Should I get the chlorine to a certain level then monitor orp at those levels and control via orp controller? Or is there a orp level that would be the right number for sanitizing a pool. I installed variable rate pumps for energy efficiency. But with the pumps running lower I can't get enough chlorine in the pool. So I'm looking to dose to keep my levels up. Thanks for all the help.

 

[Randy Holmes-Farley]

I don't know what ORP is best for sanitizing a pool. Likely in the 600's-700's, but I don't know.

 

[eagle]

Ok. Thanks. I'll be experimenting with it soon. I'll more than likely monitor chlorine levels and see what orp is and how it reacts. I have used a handheld at times and it was in 500's. Do you believe a orp controller should be used in this manner? There are so many variables to orp. I don't know if I can trust it to dose chlorine or not.

 

[Randy Holmes-Farley]

I'm not sure whether the exact chlorine level is especially well controlled by ORP, so unless you saw someone who did it and correlated with known sanitizing chlorine levels, I wouldn't do it.

 

[eagle]

Ok. I know most people that dose bleach just adjust the rate of the doser to achieve the correct chlorine levels. It's a pain. Especially on hot summer days with the sun beating on it. PH swings etc. Low ph rainwater. Def thinking about dosing borax with a ph controller. You should see a pool man when you ask him about ORP haha. Look at you like you have 3 heads . Thanks for all the help and info. Tank and pool lol.

 

[eagle]

Hi randy, I wanted to update a bit on the ORP/Biopellets. So far I have been able to see the correlation of the biopellets maturing and ORP. I've monitored nitrates and phosphates and day to day my ORP was steadily lowering as my nitrates were getting lower. My take from that is more bacteria in the water column. As I slowed the amount of water processed through the reactor my ORP slowly increases over several days. So far so good as I never saw any bacterial blooms. Another thing that has been amazing to me is I started this out only running 50 gph through my skimmer. I have the skimmer isolated in a chamber and it was only getting the feed rate through the biopellet reactor to process. Nutrient levels steadily dropped until I slowed them down from bottoming out. 50 gph is not very much at all to maintain such low levels.