Ozone generator

[ThRoewer]

I used it full force for 40 years. My Ozone generator died 4 years ago but when I get ambitious I will get another one.
No, it is not dangerous unless you stick the hose up your nose, so don't do that. Personal exprience :rolleyes:

Why not? It helps when you have a cold, just don't inhale it.

 

[Coffee Soundboard]

I’m seriously thinking about setting up an ozone system. One thing I can’t find a solid answer on is whether or not to use carbon on the export side of my skimmer. Some people seem to never use carbon this way, others do. Also, if you do use carbon on your skimmer, how are people doing it?

 

[Randy Holmes-Farley]

I’m seriously thinking about setting up an ozone system. One thing I can’t find a solid answer on is whether or not to use carbon on the export side of my skimmer. Some people seem to never use carbon this way, others do. Also, if you do use carbon on your skimmer, how are people doing it?

There's no benefit and a potential detriment (toxic oxidants entering the tank) to not passign the effluent over GAC,.

 

[Lasse]

There's no benefit and a potential detriment (toxic oxidants entering the tank) to not passign the effluent over GAC,.

Do you mean that GAC should be used for the water effluent from the skimmer if ozon is in use? I have never done that but I have used GAC in the air effluent from the skimmer in order to prevent Ozone gas to enter my living room

Sincerely Lasse

 

[Randy Holmes-Farley]

Do you mean that GAC should be used for the water effluent from the skimmer if ozon is in use? I have never done that but I have used GAC in the air effluent from the skimmer in order to prevent Ozone gas to enter my living room

Sincerely Lasse

I recommend it, yes. Ozone leaves toxic oxidants in the water. They will react with something, and if that something is a delicate organism, it may suffer.

GAC catalytically breaks down those oxidizers.

 

[Miami Reef]

GAC catalytically breaks down those oxidizers.

Is there a way you can explain what catalytically means in this scenario? Is organics don’t bind to GAC (rhetorical), would the carbon indefinitely break down the ozone-byproducts, or will the GAC eventually become exhausted?

 

[Randy Holmes-Farley]

Is there a way you can explain what catalytically means in this scenario? Is organics don’t bind to GAC (rhetorical), would the carbon indefinitely break down the ozone-byproducts, or will the GAC eventually become exhausted?

GAC can eventually become clogged with stuff that reduces the catalytic activity.

Catalytic means the ozone or the ozone produced oxidants react with the GAC surface and they break apart and are released as nontoxic products such as oxygen.

I discuss it here:

http://reefkeeping.com/issues/2006-03/rhf/index.php#17

 

[Lasse]

Ozone leaves toxic oxidants in the water. They will react with something,

Is this not the whole meaning with using ozone? To oxidise organics (including yellowing substances) and reduce organisms without defence system for different free oxygen radicals? Most "higher" organisms have a defence system. IMO - photosynthesizing organisms must have it because free oxygen radicals is a intermediate step in their waste production of oxygen.

I agree with the concern of overdosing ozone but using GAC simultaneously with ozone reduce some of the benefits you can have with it - IMO. You limit the wanted reactions to the skimmer chamber. If you use it only for water clarity (eliminate humic substances) it may works as well with only GAC but if you use it as tool to reduce an infection pressure - you will limit the effect to the water (and thus only the organisms) that pass the skimmer. In this case - a good UV-C maybe be a better (and safer tool).

Ozone is powerful and must be used with great caution but - IMO - if you use it with both suspenders and belt - maybe other technics works better and in a safer way.

I admit I have mixed feelings about the use of ozone but used correctly it can be helpful in certain situations - IMO. Unlike UV-C, ozone can also act on harmful organisms that do not pass a reaction chamber. The backslash is that ozone can also damage beneficial organisms - nitrification bacteria as an example. Ozon also contribute with oxygen gas - which favors the same bacteria. So - mixed feelings.

However - I can see where you´re coming from and maybe its a good advice for many aquarists

Sincerely Lasse

 

[Randy Holmes-Farley]

Is this not the whole meaning with using ozone? To oxidise organics (including yellowing substances) and reduce organisms without defence system for different free oxygen radicals? Most "higher" organisms have a defence system. IMO - photosynthesizing organisms must have it because free oxygen radicals is a intermediate step in their waste production of oxygen.

It might be soemone's purpose, but a better way is to have all of the desirable reactions (reduced yellowing, etc.) happening in some sort of contained volume, then remove the toxic species before returnign the water to the display tank.

FWIW, most people do not use ozone in a way that significantly kills problem organisms. Not a high enough concentration for a long enough contact period to accomplish that without using specialized equipment.

Ozone generator

I used it full force for 40 years. My Ozone generator died 4 years ago but when I get ambitious I will get another one. No, it is not dangerous unless you stick the hose up your nose, so don't do that. Personal exprience :rolleyes: Why not? It helps when you have a cold, just don't inhale it.

www.reef2reef.com

Reducing Bacteria When Using Ozone
Bacteria and other organisms suspended in water can be killed by adequate exposure to ozone. That process is widely used to disinfect drinking water and wastewater in a variety of applications. The doses and exposures of ozone required for disinfection, however, are quite high. They are higher than are used in reef aquarium applications, where typical doses of ozone range up to about 0.3 ppm in typical contact chambers, and last for only a few seconds. Consequently, aquarists must be careful when translating disinfection literature to reef aquarium effects.

In a recent study of a recirculating seawater system,35 the dosing of 0.52 ppm of ozone was tested for its ability to decrease the system's bacterial load. That dose is similar to a 300 mg/hr ozone unit applied to a typical small skimmer flow rate of 150 gallons per hour (568 L/h). In this experiment, the levels of suspended bacteria (both Vibrio and coliform) were analyzed in a variety of locations (intake, pre-ozone, post-ozone, pre-tank, and post-tank). In no case was there a statistically significant reduction in bacteria. Even the addition of a venturi injector to the contact chamber did not adequately help (although it trended toward fewer bacteria, the result was not statistically significant). For comparison purposes, at higher ozone concentrations and contact times (5.3 ppm ozone for 240 minutes), Vibrio vulnificus is easily killed, with fewer than one in a hundred million of the initial bacteria remaining.36

How much ozone, and for how long, is required to kill suspended organisms in seawater? In one study of a suspended dinoflagellate algae (Amphidinium sp. isolated from Australia's Great Barrier Reef), it was found that 5-11 ppm ozone for six hours of exposure was required to kill 99.99% of the organisms.37 While that kill rate is impressive, that exposure is far higher than is ever achieved in a reef aquarium application. Lower doses and shorter contact times had smaller effects. A dose of 2 ppm and a short contact time (with the time not stated in the paper) showed a reduction in bacteria of abut 98% (which is still quite significant, but would not be referred to as disinfection).

Similar results were found for the spores of the bacterium Bacillus subtilis.38 In this case, doses of 14 ppm ozone for 24 hours were required to kill 99.99 percent of the spores. In another study 99.9% of fecal coliforms, fecal streptococci and total coliforms were killed with 10 ppm ozone and a contact time of 10 minutes.39 The exposure of Vibrio species and Fusarium solani (bacteria that are pathogenic to shrimp) to 3 ppm ozone for five minutes killed 99.9% of the bacteria.40 Water from a seawater swimming pool was effectively sterilized using 0.5-1.0 ppm ozone in a contact tower.41

The data for the disinfection of freshwater systems are much more extensive, and so include more data at lower contact times and concentrations. In one experiment at a Rainbow trout hatchery, the addition of 1-1.3 ppm of ozone with a contact time of 35 seconds reduced heterotrophic bacteria in the aquarium water itself by about 40-90%.42

Does the ozone used in a typical reef aquarium application reduce bacteria? Maybe, but certainly not to the extent required for disinfection. Still, a reduction of 50% of the living bacteria could have significant effects. The above study in the trout hatchery showed that the use of ozone at several times the typical reef aquarium rate and for about five to ten times the typical contact time results in such a drop. While the data are unavailable, I expect that the bacteria in the water exiting a normal reef aquarium's ozone application are not decreased by as much as 50%.

It seem reasonable to conclude from such literature studies that most bacteria that enter the ozone reaction chamber in a typical reef aquarium application will not be killed by ozone or its byproducts. If killing bacteria in the water column is a goal, then a UV (ultraviolet) sterilizer may be more useful.

Reducing Other Pathogens When Using Ozone
There has been extensive analysis of the amount of ozone needed to kill the human pathogen Cryptosporidia parvum in freshwater. Most such studies are looking for significant disinfection, but some data points show the effects at lower doses and contact times, and some researchers have developed models that suggest the amount of killing at any dose/time combination.43 For example, at 22° C approximately 63% of the organisms would be expected to be killed at 1 ppm ozone with a contact time of one minute. The contact times and concentrations are inversely related, so at a contact time of six seconds, the required dose to kill 63% is on the order of 10 ppm ozone. At 0.3 ppm ozone and a six second contact time, typical for the high end of reef ozone applications, less than 5% of the organisms would be expected to be killed.

Many viruses are much easier to inactivate with ozone than are other pathogens.44 Enteric adenovirus, for example, is inactivated to the extent of 99.8% after exposure to 0.5 ppm for 15 seconds.44 Feline calicivirus is inactivated to the extent of 98.6% after exposure to 0.06 ppm for 15 seconds.44 Poliovirus type 1 was inactivated to 99% within 30 seconds of contact time at 0.15 ppm ozone.45 Hepatitis A virus was inactivated to the extent of 99.999% within one minute at 1 ppm ozone.46 Norwalk virus was inactivated by 99.9% in 10 seconds of contact at 0.37 ppm ozone.47 Adenovirus type 2 was inactivated by 99.99% by 0.2 ppm ozone with a contact time of about one minute.48

The eggs of a pathogenic helminth (Ascaris suum) were killed to the extent of 90% by exposure to 3.5-4.7 ppm ozone for one hour. One additional hour of exposure killed the remainder.49

It seems reasonable to conclude from such literature studies that many viruses that enter the ozone reaction chamber in a typical reef aquarium application may be killed by ozone or its byproducts. Larger pathogens, however, are likely much more resistant to ozone, and are unlikely to be killed. For such ends, a UV sterilizer may be more useful, but still may not be completely effective.

 

[Randy Holmes-Farley]

Is this not the whole meaning with using ozone? To oxidise organics (including yellowing substances) and reduce organisms without defence system for different free oxygen radicals? Most "higher" organisms have a defence system. IMO - photosynthesizing organisms must have it because free oxygen radicals is a intermediate step in their waste production of oxygen.

It is not generally ozone remaining in the water, but toxic species such as bromate.

http://reefkeeping.com/issues/2006-03/rhf/index.php#15

Toxicity of Ozone Produced Oxidants (OPOs)
Two sorts of toxicity studies of ozone produced oxidants (OPOs, such as bromate, hypobromous acid, etc.) are relevant to reef aquarists. The first involves the testing of seawater that has been exposed to ozone, and the second involves the testing of specific compounds dissolved in seawater that are known to form when using ozone. Most of the OPOs are unstable, and so have few or no specific toxicity studies. Bromate (BrO3-) is the notable exception, and its toxicity is examined in the next section.

Much of the study of OPOs stems from applications slightly different from aquaria, and such studies must be viewed in that light. Often they relate to aquaculture facilities, where ozone is used at high doses to sterilize the water. Other studies are done on the disinfection of wastewater using ozone, another high dose application. Bear in mind that OPOs in reef aquarium applications will be at a maximum of about 0.3 ppm in typical reaction chambers, and will be lower (hopefully, much lower) once the water passes over activated carbon (assuming it does) and finally enters the aquarium. The concentration of OPO is always given in terms of the weight of ozone that produces that amount of oxidant.

In terms of the toxicity of ozonated seawater itself, one group concluded that fish were relatively insensitive to OPOs:

"Ozonation of estuarine or marine waters can produce significant amount of bromate…Toxicity studies showed that the concentrations of bromate which theoretically could be formed in an ozonated discharge were not toxic to the early life stages of striped bass (Morone saxatilis) and juvenile spot (Leiostomus xanthurus)."50

Larvae are, in general, more sensitive to OPOs than are eggs,51 adults or juveniles.52 Japanese flounder eggs were found to be impacted by OPOs to the extent that 50% did not hatch after one minute of exposure to 2.2 ppm OPO. Larvae aged 3-15 days were killed to the extent of 50% in 24 hours at 0.02-0.05 ppm OPO. Larvae aged 44 days were killed to the extent of 50% in 24 hours at 0.15 ppm OPO. In this case, the larvae were shown to have damage to their branchial tissues.53

The eggs and larvae of Japanese whiting (Silago japonica) also have been tested for toxicity by OPOs. In this case, half of the eggs and larvae died in about 24 hours when exposed to 0.18 and 0.23 ppm OPOs, respectively.54

Certain microalgae are also relatively insensitive to OPOs (perhaps to the disappointment of many aquarists). The growth of the microalgae Tetraselmis chuii was found to be unaffected at levels up to 0.7 ppm.55 At 1 ppm, growth was impacted negatively.

Toxicity tests of OPOs on shrimp show them to be less sensitive than fish. Penaeus chinensis and Paralichthys olivaceus were found to live up to 48 hours at OPO concentrations of more than 1 ppm, while ******* halibut (fish) in the same study lived only three hours at 1 ppm and 48 hours at 0.13 ppm.56

As for other organisms, the damage to the American oyster (Crassostrea virginica) by OPOs varied with their age. Even for adults, fecal matter accumulation was reduced at OPO levels as low as 0.05 ppm.57

The effect of OPOs on rotifers (Brachionus plicatilis) has also been determined.58 No effect on survival was seen at less than 0.22 ppm OPO, but effects became significant above that level. The authors point out that bacteria and other pathogens can be killed at that level, so rotifer cultures can be used with that amount of continuous ozone to reduce bacterial contamination.

Are these levels of OPO toxicity important to reef aquarists? That is difficult to answer without knowing the levels that are attained in reef aquaria. In a typical ozone application in reef aquaria that might produce 0.1-0.3 ppm OPO in a reaction chamber, the levels are quite significant compared to potential toxicity to fish larvae and other organisms at as little as 0.02-0.05 ppm. After passing the reactor's effluent over activated carbon, the OPO concentrations should be much lower, but exactly how low is unclear and will vary considerably in different setups.

Toxicity of Bromate
The toxicity of ozone and bromate at "natural" levels in the ocean has been assessed and usually found to be minimal.59 Few studies have examined the toxicity of excess bromate itself to marine organisms.60 One review article concluded:

"Bromate toxicity tests on marine animals indicate the levels of bromate produced by chlorination or ozonation of power plant cooling waters are not acutely toxic. The LC50 ranged from 30 ppm bromate for Pacific oyster, Crassostrea gigas, larva to several hundred ppm for fish, shrimp and clams."9

One individual study showed that Pacific oysters (Crassostrea gigas) had abnormal larval development at bromate levels of 30-300 ppm.61,62 Fertilized eggs of the oyster Crassostrea virginica were killed at 1 ppm.63 The clams Protothaca staminea (littleneck) and Macoma inquinata (bent-nosed) were killed by 880 ppm.64 The marine dinoflagellate Glenodinium halli showed changes in population growth at 16 ppm.65 The marine microalgae Isochrysis galbana showed changes in population growth at 8 ppm.65 The marine diatom (Skeletonema costatum) showed changes in population growth at 0.125 to 16 ppm.65 The marine diatom Thalassiosira pseudonana showed changes in population growth at 16 ppm.65 The salmon Oncorhynchus keta was killed at 500 ppm and the perch Cymatogaster aggregata at 880 ppm.64 Two shrimp (Pandalus danae and Neomysis awatschensis) were killed at 880 and 176 ppm, respectively.64

Are these levels of toxicity important to reef aquarists? That is difficult to answer without knowing the levels that are attained in typical reef aquaria. The one study in the literature of bromate in a seawater aquarium, described above, showed the accumulation of up to 0.6 ppm bromate, although that was an application in which ozone was used for disinfection, so it was used at high doses. That level is high enough, however, to cause toxicity to certain organisms, but not others. In a typical reef aquarium ozone application, the bromate in the aquarium water is likely to be much lower. How much lower will likely depend on the way it is used, especially the dose and whether it is passed over activated carbon before entering the aquarium. It may also depend on the other husbandry practices used in the aquarium, because some procedures (such as denitrification) may reduce bromate levels. In any case, the potential toxicity data for bromate support the practice of using activated carbon after ozone exposure.

 

[Lasse]

This article may be worth reading.

Its indicate that not so much BrO3 will be formed below 5 mg/L O3 if I understand the article.

Despite the high concentration of Br− (65 mg/L), unexpectedly, BrO3− was not detected until an ozone dose
of 5 mg/L. At a relatively high ozone dose of 10 mg/L (corresponding TRO = 6 mg as Cl2/L), only 20 μg/L of BrO3− was detected.

According to the authors - its the seawaters high Br content (around 60 mg/L) that surprisingly is the reason for the low BrO3 forming!

To produce BrO3− at the final step, ozone must be available for the reaction with OBr−. Unlike for the case of freshwater ozonation, the seawater contains a high concentration of Br−, and the majority of ozone was consumed by the reaction with Br− in the first step. The OBr− concentration at an ozone dose of 5 mg/L can be calculated from the measured TRO. The TRO at 5 mg/L of ozone was measured to be 3 mg as Cl2/L (Figure S1), and from the pka value of bromine (= 8.8) and the given pH of seawater (= 8), [OBr−] can be calculated from the measured TRO. The calculated [OBr−] at that ozone dose (5 mg/L) was 6 × 10−3 mM, which is
much smaller than the Br− concentration (65 mg/L, [Br−] = 0.8 mM). Considering only the two competing reactions for the limited ozone molecules, the fraction of ozone available for reactions [1] and [3] (k3[O3][OBr−]/ k1[O3][Br−]) was calculated to be only 4.69 × 10−3. Another plausible reason for the lower detection of BrO3− with the lagged period until an ozone dose of 5 mg/L could be that the tested seawater (DOC = 1.5 mg/L) might contained some ozone-reactive compound other than Br− and that species could be initially ozone demanded.

In the article is also indicated that a high DOC can in some circumstances decrease the forming of BrO3. This correspond very well with my experiences that you need to decrease the ozone dos with time - if you want to have the same ORP reading.

I do not know but I suppose there is some connection with dose and contact time according kills of microorganisms. In a one pass chamber - you may have one result with a certain concentration but if you let the not directly consumed ozone pass out into the water column you may have the same effect with a much lower ozone concentration.

In my old aquarium I run ozone for more than 4 years but I had it knit to an ORP electrode. If I had it off for a while, the ORP readings could decrease to around 220 - 230 mV. When I start ozone again - I stated is slowly - first a nominal value of around 20 - 30 mV above the actual reading. I raised the nominal value slowly and stop around 360 - 380 mV.

Sincerely Lasse

 

[mangolove]

Super easy with an ORP controller / skimmer and it makes the fish room smell nice.

"smell nice" means you smell ozone and that is not good for your health at all.

 

[Randy Holmes-Farley]

This article may be worth reading.

Its indicate that not so much BrO3 will be formed below 5 mg/L if I understand the article.



According to the authors - its the seawaters high Br content (around 60 mg/L) that surprisingly is the reason for the low BrO3 forming!



In the article is also indicated that a high DOC can in some circumstances decrease the forming of BrO3. This correspond very well with my experiences that you need to decrease the ozone dos with time - if you want to have the same ORP reading.

I do not know but I suppose there is some connection with dose and contact time according kills of microorganisms. In a one pass chamber - you may have one result with a certain concentration but if you let the not directly consumed ozone pass out into the water column you may have the same effect with a much lower ozone concentration.

In my old aquarium I run ozone for more than 4 years but I had it knit to an ORP electrode. If I had it off for a while, the ORP readings could decrease to around 220 - 230 mV. When I start ozone again - I stated is slowly - first a nominal value of around 20 - 30 mV above the actual reading. I raised the nominal value slowly and stop around 360 - 380 mV.

Sincerely Lasse

A while back I was discussing ozone and Paul b mentioned he used it for years with “no problems”. But then, IIRC, he mentioned that the end of his refugium trough (or some related thing) grew algae poorly where the ozone laden water entered, and it grew better further downstream.

IMO, that is potential evidence of toxicity of untreated ozone water.

 

[Lasse]

IMO, that is potential evidence of toxicity of untreated ozone water

Or very high local concentration of oxygen causing problems with waste oxygen diffusion from the algae photosynthesis into the water. Or too much concentration of oxygen radicals from the O3 breakdown. I´m not saying that it was not caused by O3 but as I see it - it can have other pathways than creation of BrO3

Sincerely Lasse

 

[Randy Holmes-Farley]

Or very high local concentration of oxygen causing problems with waste oxygen diffusion from the algae photosynthesis into the water. Or too much concentration of oxygen radicals from the O3 breakdown. I´m not saying that it was not caused by O3 but as I see it - it can have other pathways than creation of BrO3

Sincerely Lasse

Sure. Bromate is not the only concern. That’s why most researchers call them ozone produced oxidants, rather than finger particular individual bad actors. Many are a concern and GAC will help deal with them.