CO2 Atomizer before In-line UV

[ObiTonyKenobi]

So I’m rebuilding my aquascape and after my experience with the Oase 250 Biomaster Thermo on my smaller tank, got an Oase 600 Biomaster Thermo for my 185 litter Waterbox 3620.

I had a a CO2art CO2 atomizer after a Fluval in-line UV filter on a Fluval 307. As I realized after I bought it, you can’t replace the UV bulb and after a year the bulb lose half of its power and it becomes useless and once the bulb dies, I have to buy a new UV filter. So I bought an Oase 7W CrystalClear and it’s big, but I can replace the bulb and play with the hoses.

Now that my tank is cycled and I’m ready to plant it and I need to put the CO2 atomizer on. The hose from the filter to the UV unit is the longest and the line to the tank is the shortest and I know the longer the CO2 travels through the hose the better. Would it be ok to put the CO2 atomizer before the UV filter, or does the UV filter have to come before the CO2?

 

[X3NiTH]

I would put it after the UV because if there is any possibility that a gas pocket could build up in the UV unit it could cause issues with flow at a minimum and at worst exposing the quartz sleeve to be exposed to a gas gap and lead to overheating the unit. Looks like the UV has a nice straight direct line on the outlet so I’d choose a few inches from the outlet to fit the inline atomiser.

If all the above was a non issue I still wouldn’t put the inline between the pump and the UV because if for any reason the pump stops and there is pressure in the inline it will flow into and pressurise the filter head, when the pump switches back on it won’t prime because of the gas gap, you have to depressurise the filter and the hoses and refill the gas gaps with water. A gas gap between the filter and the UV in the hose will render the filter unable to prime regardless of how many times you hit the priming button (your expending effort compressing the gas gap and not moving water).

If you really want to increase time in the hose to increase saturation then get a couple of double tap connectors and fit a metre of coiled hose of the same diameter with the atomiser a few inches past the first double tap connector from the UV. Stand the loop upright so that every time water goes over the top of the loop the gas wants to rise against the flow of water increasing saturation. You want to be able to remove the coil if for priming if there is gas build up so the other set of double taps connect to the hose to the tank so you can quickly remove the loop to clear it of gas if needed when priming.

 

[erwin123]

Biomaster 600 has a flowrate of 1250l/hr. If our objective is only to remove green water, 7w UV is ok

However, some purchase UV with the intention of
(1) Killing bacteria and some viruses
(2) Other pathogens.

If your objective with UV is to do (1) and (2) some sources say 7w UV is insufficient because the speed of the water flow means that pathogens passing through the UV will have 1/2 the exposure to the UV compared to say 600l/hr.

On the website, the Oase is described as a UV clarifier rather than a steriliser. i.e. It kills algae and removes 'green water', but not intended for other UV sterilization functions. On the other hand, UV clarifiers, because they don't need to maximise dwell time, often adopt a simple 'straight through' water flow rather than some flow limiting design that tries to channel the water around the quartz casing or have very narrow water channels so that all the water passes close to the quartz sleeve. In planted tanks, flow is king

ClearTronic — OASE Living Water

The ClearTronic 7W is a UV Clarifier that promotes clear water and healthy fish in your marine or freshwater aquarium up to 66 gallons (250 liters). Through the use of UV technology water from your tank is slowly exposed to a UV bulb which is ideal for preventing disease that can affect aquarium inh

us.oase-livingwater.com

 

[ObiTonyKenobi]

@erwin123 so actually that is not true about the Oase 7W ClearTronic not killing bacteria, some viruses, and pathogens because of high flow.

The Oase 7W can easily kill them or render them unable to multiply because of an obscure scientific principle called The Bunsen and Roscoe Law of Reciprocity, a photochemical reaction is directly proportional to the total energy dose, irrespective of the time over which this dose is delivered.

Basically a residence time of one second in ten passes has the same effect as a residence time of ten seconds in a single pass.
Thanks to COVID, sterilization of air in the cabin of an airplane has come up many times at work and I happen to work for that big airplane company in the Pacific Northwest and that is how I learned about that obscure photobiological scientific rule… and yes it applies to to UV Sterilizers in aquariums. One watt per 10 gallons/37.9 liters is strong enough to even kill ich throphonts.
Seven watts per 10 gallons of water would mean it’s effective for up to 70 gallons which is pretty close to what Oase says their in-line UV is effective for (66 gallons).

 

[seedoubleyou]

@erwin123 so actually that is not true about the Oase 7W ClearTronic not killing bacteria, some viruses, and pathogens because of high flow.

The Oase 7W can easily kill them or render them unable to multiply because of an obscure scientific principle called The Bunsen and Roscoe Law of Reciprocity, a photochemical reaction is directly proportional to the total energy dose, irrespective of the time over which this dose is delivered.

Basically a residence time of one second in ten passes has the same effect as a residence time of ten seconds in a single pass.
Thanks to COVID, sterilization of air in the cabin of an airplane has come up many times at work and I happen to work for that big airplane company in the Pacific Northwest and that is how I learned about that obscure photobiological scientific rule… and yes it applies to to UV Sterilizers in aquariums. One watt per 10 gallons/37.9 liters is strong enough to even kill ich throphonts.
Seven watts per 10 gallons of water would mean it’s effective for up to 70 gallons which is pretty close to what Oase says their in-line UV is effective for (66 gallons).

It’s completely. The UV won’t kill any disease if the flow rate is too high. In fact UV doesn’t kill anything, it sterilises it.

You can’t have a UV steriliser do everything unfortunately, you either have a high flow through it that will combat algae,
Or you have a slower turnover that will help combat fish disease.

I think most important thing though is to have the correct UV unit for your flow rate.

BRSTV have lots of videos on UV.

P.S I have no clue on the science and just quoting what BRSTV said

 

[foxfish]

I have nothing against UV units, in fact they are almost essential for out door koi ponds but very few people use them on a planted freshwater tank.
It just seems to be a lot of bother for so little gain, if any.
Of course if you want use one then that is cool, I really don't think it matters if you place the C02 before or after but considering that UV does not appear to have much effect and C02 has a massive effect I would put it before to give a little more run for the gas.

 

[seedoubleyou]

Who has said UV has no effect?

 

[erwin123]

You have a 185 litre tank with 1250l/hr flow, so theoretically, lets call it 1250 divided by 185 = 6.8x turnover in a hour

At the risk of oversimplification, when bacteria is exposed to the UV unit, the same bacteria will go through the UV unit again every 8.8 minutes (i.e. in 1 hour, the same bacteria will pass through the UV unit 6.8 times)

I am interested in the science, but all I have found so far in respect of Bunsen-Roscoe are experiments where the irradiation is continuous. For example, 1 mW for 30minutes continuously is equal to 5mW for 6 minutes of continuous radiation.
I haven't seen experiments where, for example, there is an 8.8 minute break between irradiation, which is what a 6.8x turnover rate implies.

 

[foxfish]

Who has said UV has no effect?

I am not sure?
UV works extremely well in the right circumstances, where I live it is used in many household water purification units where water is drawn from the ground, normally in banks of mutable 110 w units.
Also in fish ponds, for cleaning green water but not as an anti bacterial unit.
Personally I dont see much of a benefit of using a tiny unit with a fast flow on a fresh water planted tank where the emphasis is based on maintaining super clean tank and regular 50% water changes?

 

[seedoubleyou]

I am not sure?
UV works extremely well in the right circumstances, where I live it is used in many household water purification units where water is drawn from the ground, normally in banks of mutable 110 w units.
Also in fish ponds, for cleaning green water but not as an anti bacterial unit.
Personally I dont see much of a benefit of using a tiny unit with a fast flow on a fresh water planted tank where the emphasis is based on maintaining super clean tank and regular 50% water changes?

Tbf, I didn’t realise it was commonly used in the freshwater water hobby as much as I’m recently discovering. It’s used a lot more in reefkeeping where water changes are smaller and fewer.

 

[ObiTonyKenobi]

All research on UV in water systems is based on single pass sterilization, where high wattages and long residence times are very important. In an aquarium there are multiple passes of a given volume of water through a UV unit, not a single pass. So aquariums have to be treated much differently.

A good analogy I read- we can all agree that if someone lies under a sunlamp for 10 mins you are not going to get a sunburn. That is a very short exposure time. Now go under a sun lamp for 10 min every hour, 24 hours a day 7 days of the week and you will end up with a severe sunburn. It is the same with a UV filter in an aquarium. The water doesn’t just pass once, it is continuously passing over the UV filter multiple times an hour every day.

Would any of you blink at a UV light for less than a millisecond? Of course not! You would damage your eyes. Now do that multiple time an hour and you will end up blind. It's the same thing for UV in an aquarium.

Like I said earlier, a lot of research went on at work on how to kill COVID (and other pathogens in the air inside the cabin of an airliner. The air goes really fast past the UV in the cabin air filters and electrical power is a vital resource in a plane so you just can't throw in the mother of all UVs in all the filters. Again, the Reciprocity Rule of Photobiology takes care of the issue via multiple passes along with HEPA filters.

Of course a UV is not a substitute for good biofiltration, but if my fish for any reason get sick, they don't have to fight of some organisms in the water. On the same note, the fish have more immune system resources to fight of other pathogens.