Do I need to worry about dissolved oxygen in a skimmerless reef tank?

[Redzone]

I know that there have been other threads on oxygenation and skimmers but I was wondering on a practical level if people with larger tanks who go "skimmerless" have issues with dissolved oxygen levels?
I have a 195 gallon (72x26x24) aquarium with an 80 gallon sump (60x18x18). I have about 175 pounds of Fiji live rock in the display and 2 large blocks (8x8x4) and 2 small blocks (8x8x1) of marinepure in my sump. My phosphates and nitrates were undetectable (also running GFO and using a skimmer) . However, I was having a lot of trouble keeping SPS colored and LPS alive and at the same time was fighting red turf algae that my rabbitfish would not touch (he prefers pellets). About 3 months ago I made major changes, took out the skimmer and gfo, started growing cheto in my sump instead and added two tangs to help with the algae. Since then my corals are thriving and the turf algae is better controlled by the new tangs. But am I missing anything? Should I be concerned about having sufficient dissolved O2 without running a skimmer? If so, what should I be monitoring?

Current fish are:

3 Carberryi Anthias
2 skunk clownfish
Blue Spotted Rabbitfish
Small Desjardini Sailfin Tang
Small Orange shoulder tang
Longfin wrasse
Upsidedown goby ( Bryaninops nexus)
Blue Mandarin

I plan to add two more small wrasses and a pair of Bellus Angels in the near future.

Current parameters are:​

Nitrate 0.65 ppm
Phospate 0.00
Alkalinity 7.2
Specific gravity 1.025
Temp 77-79
ph 8.1-8.45
ORP 415-430

My powerheads are 2 vortech MP40s and one neptune WAV. I use a calcium reactor.

 

[M Stein]

Haven't tried running a large system skimmerless yet but here are my thoughts.

You have
1) very few fish relative to your water volume (Fish consume oxygen)
2) You're running a refugium (Plants produce oxygen)
This being the case I doubt you'll have any trouble especially if you're see good results. Either way, the parameter I would watch is PH.
In my 15 nano I have a high bio-load (5 fish, one of them a yellow tang) and no skimmer or refugium. My PH is routinely low <7.8. I'm working on using Kalkwasser to raise it, but so far I haven't seen any negative effects from the low ph. (raising the ph for a week seems to have accelerated the growth of the coral though).

 

[Poof No Eyebrows]

Haven't tried running a large system skimmerless yet but here are my thoughts.

You have
1) very few fish relative to your water volume (Fish consume oxygen)
2) You're running a refugium (Plants produce oxygen)
This being the case I doubt you'll have any trouble especially if you're see good results. Either way, the parameter I would watch is PH.
In my 15 nano I have a high bio-load (5 fish, one of them a yellow tang) and no skimmer or refugium. My PH is routinely low <7.8. I'm working on using Kalkwasser to raise it, but so far I haven't seen any negative effects from the low ph. (raising the ph for a week seems to have accelerated the growth of the coral though).

Roger dispatch, Tang police en route to apprehend.....

 

[Poof No Eyebrows]

In all seriousness your probably just fine. Do you have good surface agitation from your return / power heads?

 

[M Stein]

Do you have good surface agitation from your return / power heads?

Yes. But tank is also next to my bed, so the most drastic drops happen at night when I'm filling the room with co2.

 

[Auquanut]

I'm kind of in the "you can't have too much oxygenation" camp, BUT I'd say that your PH looks really good which tends to indicate that you don't have excess CO2 in the system. As long as you have good surface agitation through the display and sump, you're fine. As your bioload goes up, your PH may drop some, but then you'd probably want to put the skimmer back on line as the nutrients start to rise anyway. I wouldn't worry too much about your current nocturnal PH drops. It still looks really good in my opinion.

 

[Timfish]

How air tight is your house? Have you tested your house's CO2 levels? Low oxygen in skimmed tanks can be an issue depending on air exchange in a house or with tightly sealed tanks and stands. Good surface agitation will help both gas exchange, both adding oxygen and getting rid of CO2. Considering the research showing air pollution is higher inside than outside having a small air pump outside may always be advisable for reef systems. FWIW this link has oxygen levels at Palmyra Atoll if you want a refference to use.

 

[Redzone]

In all seriousness your probably just fine. Do you have good surface agitation from your return / power heads?

Some surface agitation but not a lot. I will work on this.

 

[Redzone]

How air tight is your house? Have you tested your house's CO2 levels? Low oxygen in skimmed tanks can be an issue depending on air exchange in a house or with tightly sealed tanks and stands. Good surface agitation will help both gas exchange, both adding oxygen and getting rid of CO2. Considering the research showing air pollution is higher inside than outside having a small air pump outside may always be advisable for reef systems. FWIW this link has oxygen levels at Palmyra Atoll if you want a refference to use.

Its a old house, lots of fresh air indoors...

 

[Breadman03]

Its a old house, lots of fresh air indoors...

I get that. My curtains sway with pretty much any breeze. I'm actually setting up a wood shop almost exclusively for building a tank stand and restoring my windows.

 

[Randy Holmes-Farley]

Very few people with or without skimmers measure O2.

IMO, it is a potential concern, especially in a skimmerless tank.

 

[Redzone]

Thanks! How should I measure O2?

 

[Randy Holmes-Farley]

Thanks! How should I measure O2?

It is not trivial, which is why more people do not do it. Kits may not be adequately useful.

Eric describes using an expensive meter here:

http://www.reefkeeping.com/issues/2005-07/eb/index.php

 

[Redzone]

It is not trivial, which is why more people do not do it. Kits may not be adequately useful.

Eric describes using an expensive meter here:

http://www.reefkeeping.com/issues/2005-07/eb/index.php

Does anyone have experience with any hobbiest grade 02 probes and meters, for example RC-YAGO?https://www.amazon.com/gp/aw/d/B08N..._0?ie=UTF8&psc=1&pd_rd_i=B08NFYY4L8p13NParams

 

[DxMarinefish]

You could also run the skimmer but don’t collect the skimate...that’s what I do. I run 2x ATS and will only collect the skimate if my nutrients rise.
My skimmer air intake is fed from outside.

 

[jdiefenbaugh]

Does anyone have experience with any hobbiest grade 02 probes and meters, for example RC-YAGO?https://www.amazon.com/gp/aw/d/B08N..._0?ie=UTF8&psc=1&pd_rd_i=B08NFYY4L8p13NParams

I never understood why these meters are so expensive. I have only used OxyGuard and Hach, neither has a hobby friendly price point. I don't know how accurate the salifert test is, but you're only out $20 if it doesn't work.

 

[Randy Holmes-Farley]

I never understood why these meters are so expensive. I have only used OxyGuard and Hach, neither has a hobby friendly price point. I don't know how accurate the salifert test is, but you're only out $20 if it doesn't work.

But you might also be misled on the values if it is not sufficiently accurate. it would at least require extra controls, such as very well aerated aquarium water as a standard.

 

[Randy Holmes-Farley]

Does anyone have experience with any hobbiest grade 02 probes and meters, for example RC-YAGO?https://www.amazon.com/gp/aw/d/B08N..._0?ie=UTF8&psc=1&pd_rd_i=B08NFYY4L8p13NParams

I've seen very few people report O2 values of any kind.