Uv Sterilizer In A Large High-tech Planted Tank Vs Fertilization And Nutrients?

aeneas

New Member
Feb 15, 2021
11
1
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Slovenia
Hi guys,

as some may have seen in another thread, I am building a 290gal freshwater high-tech planted aquarium; CO2, AWC, automated nutrient/fertilizer dosing etc.

I was intending to add a UV unit as well in a bypass on the return pipe - after the CO2 reactor. The idea would be that in a tank with many expensive discus and altum fish I would not only want to reduce algae (will have lots of algae clean-up crew such as ottos and amanos anyway) but also to limit any potential infections for the fish.

However, I've been doing some additional research on UVs... it seems for my intended flow (~1,200-1,500 gph) there are only a few UV sterilizers that could support such flow (even in a bypass setting) - and these are priced between $500 and $1000. Now, long-term, I would not upfront reject a high investment if it really added value.

However, many comments and reviews seems to be unclear whether UV really helps or not, while on the other side I read some concerning comments that UV might degrade/chelate various micronutrients that I will be adding to the tank for plant fertilization etc. I would certainly not want to destroy a fertilization effort...

Any thoughts on this?

Do people switch on/off UV sterilizer depending on the days of IE fertilization etc. or what is the general consensus and recommendation here?
 
I would be interested in a response to this as well. I have a rack of aquariums on a common system, which gives me a total volume around 120 gallons when counting dual sump capacity. I have a flow of about 600gph, but it needs to be increased a bit to boost the flow to the higher aquariums in my rack. I'm employing a 25W UV Sterilizer (LifeGaurd Aquatics Pro-MAX) that follows my large CO2 reactor... I took care to build in a by-pass on the CO2 reactor, but do not have a bypass on the UV Sterilizer. So, I'm hoping that I get enough dwell in this unit to be effective (it's rated at 1000gph). I like it (mine is older, so I don't have the 'bulb time counter', so I just have to remember to change the bulb between Nov/Dec. I'm dosing nutrients, but need to continue to learn more to do so effectively... when I have a handle on that, I will turn that over to the dosing function on my homemade DIY aquarium controller.

There is a 55W version of this UV Sterilizer available as well which supports upto 3500gph and upto 350gallons. It's a bit large in terms of it's length, but it's certainly well below $350usd (if you are in the USA and use Amazon it would be cheaper). It uses an Amalgam bulb, and I don't know if that has different 'destructive' properties than the standard hight output bulb that my 25W unit uses and whether it degrades micronutrients.
 
I would be interested in a response to this as well. I have a rack of aquariums on a common system, which gives me a total volume around 120 gallons when counting dual sump capacity. I have a flow of about 600gph, but it needs to be increased a bit to boost the flow to the higher aquariums in my rack. I'm employing a 25W UV Sterilizer (LifeGaurd Aquatics Pro-MAX) that follows my large CO2 reactor... I took care to build in a by-pass on the CO2 reactor, but do not have a bypass on the UV Sterilizer. So, I'm hoping that I get enough dwell in this unit to be effective (it's rated at 1000gph). I like it (mine is older, so I don't have the 'bulb time counter', so I just have to remember to change the bulb between Nov/Dec. I'm dosing nutrients, but need to continue to learn more to do so effectively... when I have a handle on that, I will turn that over to the dosing function on my homemade DIY aquarium controller.

There is a 55W version of this UV Sterilizer available as well which supports upto 3500gph and upto 350gallons. It's a bit large in terms of it's length, but it's certainly well below $350usd (if you are in the USA and use Amazon it would be cheaper). It uses an Amalgam bulb, and I don't know if that has different 'destructive' properties than the standard hight output bulb that my 25W unit uses and whether it degrades micronutrients.

What I like about the LifeGaurd products is that parts are available. I had foolishly glued in adapters that were too small in the 2" inlet/outlet slip fittings. I was pleased to be able to order 2 new ones for under $20usd, which allowed me to fit in larger adapters when I re-plumbed my system to 1" piping.
 

Deanna

Member
Aug 23, 2018
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PA
I’ve used a “level one” sterilizer for well over 15 years. I consider it to be an important piece of equipment for an aquarium. It will destroy bacteria and viruses, as well as some algae spores. However, it will not prevent algae …just impede it a little. Since owning this, I have had no illnesses in my fish that I can attribute to a vector.

A UV sterilizer doesn’t necessarily kill anything, although we often talk about it as having killing power. What it primarily does is to sterilize life so that it cannot reproduce. Parasites in their free-floating phase, such as Ich, are harder to sterilize, so slower turnover is better for them. Bacteria and algae are easier to sterilize and, although slower flow ensures it, turnover needs to be high enough to keep up with their incredibly fast reproduction rates and this is where a minimum turnover rate comes into play.

Another consideration is that turnover is more than just measuring gph. The circulation in the tank should be good enough to ensure even distribution of water throughout the entire tank. This gives the UVS the chance to come into contact with a well-mixed solution.

Important to get a high-end one, not the cheapies on Amazon that will just clear-up green water. It’s the difference between a “clarifier” and a sterilizer. The ‘kill’ capability is a combination of microwatt seconds per square centimeter and temperature. You want a sterilization capability with as high a dwell time as you can find. Look for a UVS that has "Level 1" sterilization capability. Specifications to focus upon are microwatt seconds per square centimeter (µW/cm2 in spec sheets) and dwell time (gph). Basically, a high µW/cm2 unit will allow higher flow rates for a given kill capability.

Although you do have to change the bulb at least once per year, switching it on and off will reduce that to every 8-10 months.

Regarding micronutrients, yes; a UVS will rapidly rip apart chelators. If your pH is above ~6.5, this means that many of the the traces will precipitate out, possibly before the plants can use them. Because of this (and other reasons), I use iron gluconate (Flourish Iron) and make my own trace mixes out of non-chelated compounds. However, if your pH is below ~6.5 (I intentionally keep it in the 5.5-6.0 area) you won’t have those solubility/precipitation issues if your traces are no longer chelated. In fact, for a planted tank, the 5.5-6.0 pH range is the optimal uptake/availabilty region for ferts. Although, some species of fish do better with higher innate pH. Many of us, UVS or not, have found that daily dosing of traces is best for many of the above reasons.
 
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Stan510

Member
Nov 28, 2019
188
12
18
Hayward ca.
IF I had Discus in that size aquarium? UV would be a must.
I had never heard that UV breaks down trace elements. But,I never have used one myself. Still,seeing some of the best Koi ponds in Europe have them as those fish have to cope with very cold winters stress tells me they get things done. Jacob on youtube also says he thinks they are a great addition..he's seen gray water issues taken care of by even a hobby UV system.
 

aeneas

New Member
Feb 15, 2021
11
1
3
43
Slovenia
I’ve used a “level one” sterilizer for well over 15 years. I consider it to be an important piece of equipment for an aquarium. It will destroy bacteria and viruses, as well as some algae spores. However, it will not prevent algae …just impede it a little. Since owning this, I have had no illnesses in my fish that I can attribute to a vector.

A UV sterilizer doesn’t necessarily kill anything, although we often talk about it as having killing power. What it primarily does is to sterilize life so that it cannot reproduce. Parasites in their free-floating phase, such as Ich, are harder to sterilize, so slower turnover is better for them. Bacteria and algae are easier to sterilize and, although slower flow ensures it, turnover needs to be high enough to keep up with their incredibly fast reproduction rates and this is where a minimum turnover rate comes into play.

Another consideration is that turnover is more than just measuring gph. The circulation in the tank should be good enough to ensure even distribution of water throughout the entire tank. This gives the UVS the chance to come into contact with a well-mixed solution.

Important to get a high-end one, not the cheapies on Amazon that will just clear-up green water. It’s the difference between a “clarifier” and a sterilizer. The ‘kill’ capability is a combination of microwatt seconds per square centimeter and temperature. You want a sterilization capability with as high a dwell time as you can find. Look for a UVS that has "Level 1" sterilization capability. Specifications to focus upon are microwatt seconds per square centimeter (µW/cm2 in spec sheets) and dwell time (gph). Basically, a high µW/cm2 unit will allow higher flow rates for a given kill capability.

Although you do have to change the bulb at least once per year, switching it on and off will reduce that to every 8-10 months.

Regarding micronutrients, yes; a UVS will rapidly rip apart chelators. If your pH is above ~6.5, this means that many of the the traces will precipitate out, possibly before the plants can use them. Because of this (and other reasons), I use iron gluconate (Flourish Iron) and make my own trace mixes out of non-chelated compounds. However, if your pH is below ~6.5 (I intentionally keep it in the 5.5-6.0 area) you won’t have those solubility/precipitation issues if your traces are no longer chelated. In fact, for a planted tank, the 5.5-6.0 pH range is the optimal uptake/availabilty region for ferts. Although, some species of fish do better with higher innate pH. Many of us, UVS or not, have found that daily dosing of traces is best for many of the above reasons.

@Deanna thank you for this very informative post. I've spoken to my local supplier here who installed also my current water softener and RO system etc and they proposed to use Viqua VH410 UV system, which is actually intended for UV sterilization of household water supply and handles 4200 l/h at 30mJ/cm2. Pretty powerful it seems, but the price is close to $1000. Alternative is AquaMedic Helix Max - I already have a 36W which is probably underpowered, but could swap it for 55W. That one comes almost 4x cheaper... Would it still get the job done or should go for the "pro" and expensive Viqua system?
 

kizwan

Member
Aug 17, 2019
102
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Kedah, Malaysia
Increase contact time. So instead using faster pump, use slower pump for UV. More contact time, more effective the UV will be.

UV will sterilize any free floating algae, spores & bacteria but it will not 100% prevent algae.
 

Paul G

Lifetime Charter Member
Lifetime Member
Sep 28, 2011
129
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Independence MO
Sorry I'm coming a little late to this discussion. Proviso: I speak only of planted freshwater display aquariums.

I used UVC for a very long time. I ran multiple tall LifeGard units on my 210 gallon jungle style planted tank. When I turned them off, I had no infections from pathogens afterwards, ever. Observed hygiene and water care assiduously, quarantined new fish for two weeks or more, all the precautions. No sick fish for two years and no UV. I wondered also about the effects of UV on supplements, so I actually did the experiment.

I test my water almost daily for all these: NO3, PO4, Fe, K, Ca, Mg, KH. Yes, really! I use LaMotte and Hanna kits. UV exposure will not alter inorganic salt solutions such as K2CO3, KNO3, Ca(NO3)2, MgSO4, K2SO4, KH2PO4, CaCl2, etc. These are simply ions in aqueous solution, and that includes alkalinity. There is nothing present that is further altered by ionizing radiation. What ionizing radiation will alter are organic molecules. UV exposure works by denaturing a molecule, causing structural distortions and compositional changes. Many biologically active organics are subject to photolysis even in light of ordinary visual wavelengths and can easily be destroyed by intense UVC irradiation, particularly complexes, such as some chelates that are weakly bonded.

I run a streaming water change regime, and auto-dose micronutrient daily. All the iron going into the water is as ferrous gluconate. The Hanna photometer will report non-zero Fe at all times, day and night. I keep Fe at between 0.2 and 0.6 ppm. Iron is always present in this aquarium. I have done this test twice: test Fe in the morning, turn on the UV all day, then test Fe in the evening. Iron after several hours of UV exposure is undetectable - zero, zilch, nada. The UV photolysed the ligand, the iron anion associated with a PO4 cation and precipitated out as an insoluble salt. It probably happens with other complexed micros. It is essential that a chelate breaks down at some point so that the metal can be released and utilized as intended. Chelates are weakly bonded by design. Zap a chelate with some shortwave photons, and it will let go of its metal for sure and always. If the iron is precipitating out, so is the manganese, etcetera and soforth. By the way, gluconate is a short-chain sugar and is a different kind of complexer from a conventional chelator, but it is not immune to photodecomposition, as my test shows.

If I don't detect iron in the water column, I can't know that the iron in my aquarium is bio-available. Any bio-available iron in the substrate available to the roots is a separate question. So I must accept that the UV light used today has destroyed the liquid iron fertilizer that I added to the tank this morning, and there will be no foliar uptake of ferrous gluconate until the UV light is turned off and some fresh fertilizer has been added once more.

What else? Have no means to hand for testing these, but consider any organic molecule, aliphatic or aromatic. It's very possible that shortwave photons can denature them, so you must assume that they can't be trusted with UVC radiation as you have no way of knowing differently. Excel, peptides, amino acids, and phytohormones, such as are found in Advance? Probably these are altered by UV.

The point is, if you are doing everything right and your tank is healthy, what need is there for UV? I had a big investment in my UV equipment but eschewing it was a no-brainer for me.
 
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