Oxygenation

[+KeeperOfTheZoo]

For those of you that test, what does your oxygenation level run? After talking with a LFS owner about my set up he told me I probably have really low Ox levels (he said he'd be surprised if it was 2). So I got worried and bought a test kit.

Like most it's color graduated. First thing in the morning my ox level is at least 7 (much darker than 6, not to 8). At the end of the day with lights running it's just a bit lighter than 10. So, I'm thinking my oxygen levels are at least meeting the min needed. Or should I really be trying for higher levels? My fish are all active and breathing fine.

I was also told to get rid of all my powerheads (because they don't contribute to oxygenation) and get a big (mag 1800) return pump for all my circulation/oxygenation. Thoughts on this? My current return is pathetically small, I have a mag 7 I'm going to be using shortly. I thought that plus powerheads would be fine for a softies /LPS tank but if powerheads really don't count for turn over then that mag 7 is also a pathetically small pump for a 125g.

Hmmm.....

[+Hydro]

I'm not sure about the oxygen levels, I just bought a meter to test it but haven't used it yet. But I do know that a Mag 7 is to small for your tank for sure. You should rate your pump GPH slightly bigger than what your overflows will allow to quietly flow. You should have a PVC ball valve in line with the pump supply line so that you can decrease the flow to what you need. I'm going to guess that you need a mag 9.5 for your tank, that is what I had on my 175 with (2) 1" overflows, I now use a much larger pump than that b/c I'm running several pieces of equipment with it.

I wouldn't get rid of the powerheads, they do more for you than just oxygenation like keeping dietrius from collecting behind your rocks. And besides if they move water at the surface level then they are adding oxygen. If you had a bucket of water with no movement sitting for a week and had another bucket with a powerhead churning the water there would be a big difference in oxygen levels, so I have to say I don't agree with that. We use powerheads in the gardening industry to oxygenate nutrient reservoirs with 0 problems with oxygen levels for the plants.

[+dapettit]

I wouldn't get rid of the powerheads, they do more for you than just oxygenation like keeping dietrius from collecting behind your rocks. And besides if they move water at the surface level then they are adding oxygen. If you had a bucket of water with no movement sitting for a week and had another bucket with a powerhead churning the water there would be a big difference in oxygen levels, so I have to say I don't agree with that. We use powerheads in the gardening industry to oxygenate nutrient reservoirs with 0 problems with oxygen levels for the plants.

+1 keep you powerheads!

[+KeeperOfTheZoo]

I don't have a drilled tank so my overflow is based on what ever box I get. I have a 800gph CPR overflow that I'm getting ready to switch over to so that, numbers wise, works fine with my mag 7.

I guess I should clarify my question. I'm not concerned with high turn over through my sump/fuge if the oxygen levels I'm maintaining at now are OK. I have primarily softies with a few LPS & SPS. My original plan would set my tank turn over at about 16 tph, not counting the skimmer. That's plenty, unless powerheads don't count.

Now, I do have one of my current powerheads set up to agitate the surface of the tank and my tank is open top.

I'd really like to know what good/ideal oxygenation rates are to avoid the long term problems I was warned against.

And yea, I think Ill hold onto my powerheads.

[+dapettit]

What long term problems?

[Mike M.]

If you are running a skimmer, I don't know that I'd worry about this issue. If no skimmer, then turnover as instructed above is important. If a skimmer is bubbling away, gas exchange is definitely occurring.

[Timfish]

When I first started doing maintenance 15 years ago I tested for oxygen regularly but it's probably been a decade since I tested for it in any of my tanks. Reasons i stopped (if I remember correctly ) animals almost always will tell you there's a problem before tests will and if water changes are being done weekly, biweekly or monthly and there's good flow oxygen will always be good. I'd put more emphesis on pH as that will indicate a build up of CO2 which can be high even with a good oxygen reading.

[GKarshens]

As mentioned if your powerheads are causing surface agitation they are causing gas exchange. Also as said above a skimmer will add a lot of oxygen to your water. I am not a huge proponent of high turnover rates through the sump. I feel you give your filtration, either skimmer or fuge, time to do its job.

[+KeeperOfTheZoo]

Thank you everyone, you've pretty much covered the thoughts tumbling around in my head. Im still too new at reef keeping to not second guess myself and there are so many opinions on how tanks should be run. I think a lot work, but only in conjunction with a series of other practices and it gets confusing.

I run my skimmer 24-7 and do bi weekly water changes.

I'm not exactly sure what all the long term consequences would be but I think nutrient build up leading to failure of the tank was the big one, and of course livestock suffering.

Don't quote me but the overall method being advocated was a CC bed (no sand), very high turn over via a return pump, massive amounts of biological filtration via tightly stacked live rock, minimal feeding of the fish and water changes only every 4-6 weeks. I'm sure there's more to it than that as well.

[+KeeperOfTheZoo]

Tim, I asked about pH and how it's affected by co2 and had that idea get kinda blown off. So what would pH do if ox was low? Would you expect to see a rise in co2 and low pH?

I agree about livestock showing signs of stress. That was the first thing my hubby said when I told him I blew $20 on a test to make sure my fish had enough ox.

[GKarshens]

Sounds like the advice was from someone pretty old school. That thinking has definitely changed over the years.

A build up of CO2 will cause the PH to drop. That is one big reason for surface agitation. Also if your tank has bracing it helps to have a fan blow across the surface, as CO2 is heavier than oxygen. It can kind of form a blanket over your tank. I had a problem with PH when I first started and this solution was offered to me. Added a fan and no more issues.

[+KeeperOfTheZoo]

Gabriel, do you think co2 build up would be an issue with an open top tank? Aside from aesthetics, one of the reasons I've been avoiding a canopy is to promote good ox levels. I do have a big glass center brace on my tank.

Is it possible to have high co2 and oxygen? I figured it would be one or the other as living thing consume oxygen and produce co2, though I'm sure that some ox is being produced by algae growth. I knew high co2 would suppress pH. My pH has always been right in range.

So much to learn!

[GKarshens]

An open top definitely helps. The brace could help hold the CO2 over the surface of the water. However, if your oxygen levels are good as well as your PH, it sounds like you are in good shape.

[Will]

O2 and co2 can disolve in saltwater I dependently if one another, so theoretically you could have high levels of both.

The method you listed above would cause alot of dead spots in your rock work that will cause you alot of problems. I would have your system pump turn over your tank a minimum of 5x per hour. I would have a fairly open scape, sand ( shallow bed ), and powerheads to move the deoxygenated water at the bottom of the tank to the top for gas exchange

[Timfish]

. . . so many opinions on how tanks should be run . . .

Really!? Hadn't noticed

[Timfish]

Tim, I asked about pH and how it's affected by co2 and had that idea get kinda blown off. So what would pH do if ox was low? Would you expect to see a rise in co2 and low pH?

To be honest I don't know what oxygen would do if the pH was low. It's been so long since I bothered with testing oxygen I don't remember any details just that it didn't really help identify problems.

If I'm remembering my chemistry right (anybody out there feel free to update me) CO2 combines with calcium carbonate making carbolic acid which lowers pH. CO2 is also MUCH harder to degas or get rid of out of water than oxygen is to dissolve in or add to water so with good water flow usually water is well oxygenated but if there is a lot of CO2 from whatever cause pH will drop. It's my perception that CO2 and oxygen are not mutually exclusive or have an inverse relationship but but both can be high or both can be low. Obviously we want high oxygen and low CO2. I think this is partly why many people advocate high turnover rates or flow rates in tanks to facilitate gas exchange. Like GKarshens I'm not stuck on having high flow rates through a sump. I've also had equally good success with Lee Chin Eng's methodology which doesn't use sumps or pumps as any other system but I prefer a system with a sump for greater surface area for gas exchange and system volume.

In practice I don't religiously test my water but I like having a history of the pH. I start looking for problems when I see a noticable or prolonged change in the pH from what it historicaly was for that tank. For example a pH of 8.2 is typically considered good for a tank but if for the last year it was at 8.4 I'm going to start worrying and start checking my other parameters and maybe preemptively do a real big water change but certainly start monitering it more closely.

[Bill B]

Sounds to me like you've been talking with Shane. I thought his eyes were going to pop out of his head when I once told him I had just under 500 gph on the return for my 75. I'm sure his methodology works for him but I'm sure it's not the only way to do stuff.

Bill

[+KeeperOfTheZoo]

. . . so many opinions on how tanks should be run . . .

Really!? Hadn't noticed

Yea, yea. But I'm great at stating the obvious, right?

Hey, I didn't miss that treky response to my weird sponge and critter post. I just had to shudder at the fact that I got it. That's what happens to a girl after 16 years of being married to a star wars/trek junky. I get that stuff. Ugh.

[+KeeperOfTheZoo]

Thanks Tim, as always I love your replies. I'm gonna check oxygenation problems off my list of concerns. With an open top tank and 40g of open top fuge/sump under the tank I don't think it's gonna be an issue. Especially once I upgrade both my return pump and my power heads. My fish and I can both breath easy now (not that they weren't all along, silly me I'm the one having panic attacks).

I've been testing less and less as I relax into maintaining the tank. The other day my pulsing xenia just weren't pulsing quite as vigorously as usual. I tested and for the first time my pH, kH and calcium had dropped below where I'm happy with them being (pH was 8, kH was 7, calcium was 380). I dosed the tank for the first time, 8 months into having it. Being me (ie- paranoid) I did it slow over a couple days.The xenia perked right up. I've read in a couple different places that xenia are a great 'canary in the mine', I think I'm going to believe it. It's a little silly but I was rather pleased with myself for noticing & catching the issue before it got truly bad. My kH is back up to 9 pH 8.3 and my calcium is at 420 (normal numbers for my tank), I'm happy with that. I have a lot more calcerous growth going on and knew I'd probably have to dose soon. Now I just have to test and see what dosing schedule will hold the parameters there.

Thanks everyone, and yep Bill, I talked to Shane. I figured someone would catch onto that but I wasn't gonna mention names. He is a fascinating guy to talk to and very different in his approach compared to most of what I've read. I'm not sure I agree 100% and he was obviously wrong about my oxygen levels, but I do think it'd be interesting to set up a tank the way he advocates. He has some of the best looking tanks/stock of any of the LFSs.

[Timfish]

Thanks Tim, as always I love your replies.

Thank You! I try not to take anything any more serious than my cats take me, except float valves and check valves, don't like either one of them.