# Elodea started to decalcify — are my lights too strong?



## cygaj (Jan 30, 2018)

I started to see white calcium (? it seems so) film on my waterweeds. I've read that it might lead to dangerous PH swings between day and night so it worries me. I removed a couple of the most grown out plants that have the white stuff well visible on them and I reduced my photoperiod slightly for now.

I have a 160l (~42 US gallon) tank with soil at the bottom, some lignite sprinkled on it (also a bigger pieces of lignite lying as rocks), with a play sand cap. It's two weeks old. At the moment it has 10 WCMM, a couple of RCS, an apple snail, a military helmet snail, and some MTS and tadpole snails. It's densely planted with cabomba (I don't think it survives for long, it seems too delicate for a total novice like me to keep), hygrophila, and the elodea. There also are other plants in smaller numbers I bought or got from friends: myriophyllum, pistia, cryptocoryne, rotala, bocopa, lymnophila, vallisneria, some other grasses, mosses, specks of duckweed, etc… Attached photo of whole tank was taken moments ago, after some of the waterweeds were already cut out.

I have three 24W T5 lights over it on for ~3.5h in the morning and ~4.5h in the evening. Is the light too strong? should I install something weaker? Or maybe I need more animals to produce more CO2? It matters to me to not add any CO2 or dose liquid fertilizers, I'd much rather work on an arrangement now that will go low-maintenance in the long run.

I intended on thinning down on waterweeds after I've got other plants going, because I was worried it's just gonna dominate and it's not my favourite, so I wouldn't mind getting rid of it if it's dangerous or something… What plants are safer for fauna?

Most importantly: should I be worried? Does it sound bad enough to be worried? Or is it normal for elodea in some small degree and not always leads to dangerous situation?


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## Michael (Jul 20, 2010)

Welcome to APC!

I am not at all familiar with this phenomenon, but your general description of the tank sounds fine. Have you done any water tests and what were the results?


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## hoppycalif (Apr 7, 2005)

If you are not going to use CO2, dose Excel, or dose any fertilizers, you need to use only low light. Otherwise you won't have enough nutrients to support the higher growth rate the light is driving the plants to. And, that usually results in unhealthy plants, which attract algae. I don't know anything about the lights you are using, so I can't do an accurate guess about how much light you have, but, I think 3 T5HO lights would give you more than low light, unless they are suspended some distance above the top of the tank, or have no reflectors.

What light fixture(s) do you use? Do you have a good photo of it, that shows the bulbs and the reflectors?


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## cygaj (Jan 30, 2018)

The bulbs are all sylvania (I think there are two different kinds, at least I can tell apart two different colors by sight), they have reflectors, one of them is off so only three are on. I got the entire tank cover with lights second hand. I'd like to change the setup anyway, so the hood could support the weight of my cats safely, without worrying about it bending down if any of the two decides to jump on the aquarium. What would be the good wattage per liter or kind of lights I could use? Preferably on the weaker side so I could extend the photoperiod safely&#8230; What is considered low light? My tank is 50 cm high and the substrate is 6-10 cm thick.

I don't have water tests and I'm trying to do without them for now but I could always end up getting a PH test for example if it's necessary after all.

PS. I'm reposting the photos I posted earlier in higher res too.

EDIT. Would it help if I figured out how to turn off one bulb more? So I'd be left with 2x24W T5? If anyone has answers to my previous questions (what is considered low light, what lights are appropriate, etc) I still would appreciate them because I'd ultimately welcome a new cat friendly cover on my tank.


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## hoppycalif (Apr 7, 2005)

It looks like you have good reflectors on the bulbs. I would expect each bulb to be giving you about 40 PAR at about 50 cm from the lights. With two bulbs you would get about double that, but the bulbs are shorter than the tank length, so the light intensity would drop quite a bit near the ends of the tank. Three bulbs would give you about 3 times that. 40 PAR is low medium light. 80 PAR is high light. For a discussion about light on an aquarium see http://www.plantedtank.net/forums/10-lighting/184368-lighting-aquarium-par-instead-watts.html

Are you able to make your own tank cover out of wood? A cheap way to get what you need would be to make a plywood box that will sit on top of the tank securely, and mount two of those lights, with their ballast in the box, only I would try to get the next longer size bulbs, so the come closer to matching the length of the tank. What ballast does the light use - manufacturer and part number? If you don't know what a ballast is, it is an electric component, with a power cord in one end and colored wires coming out the other end, with the wires going to the end caps that are on the ends of the bulbs.


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## cygaj (Jan 30, 2018)

I've been reading about lightning for good part of the day and in the end I decided to commission a wooden cover because I'm worried about my cats breaking it and getting shocked so I don't want to make my own since I don't know anything about woodworking. I found a person on an ad website that does tho and he's an aquarist so he both knows his material, its strength, and how to apply his skills for aquarium use. I gathered the courage to ask him about his prices and it turned out that they're affordable for me. It's gonna be safest for my cats plus I'm willing to pay for something well made.

I figured that I'll buy a bare cover and install a single T5HO in it, closer in length to the length of my tank, but I asked him what kinds of lights he installs in the covers for his clients. He said that for my aquarium it would be a 16W LED fixture from Diversa. So I figure it would be something like this.

The question I'm trying to answer right now is whether 16W 65cm of LED over a 50cm high tank would be considered a low light or close to it. I'm still trying to research and understand it but I figures that in the process I could post here about this idea because maybe someone has the answer on hand. It says on the page that it's 1800 lumens, if it's the light in question of course.

When it comes to my ballast, this is it:








I got my dad to help and we tried to disconnect one of the bulbs but it turned out to be impossible because they're connected serially. Tomorrow we'll try to turn on the forth one and make it replace the other three for the time being. It has it's own ballast and I couldn't turn it on when I was starting the aquarium so I didn't bother because I didn't need so much light to begin with.


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## hoppycalif (Apr 7, 2005)

I have been using LED lights for several years now, and love them. The secret to really enjoying them is to be sure you have some horticultural LED light strips in your light, with the rest a natural white. That lets it look like just white light, but the additional near infrared red LEDs and near UV blue LEDs make the colors of the plants and fish really show very well. That light you linked to is made from the same type of LED tapes I use, so they could include about 10% horticultural LEDs if the maker wanted to include them.

It isn't hard for the manufacturer to measure the light intensity from his lights, at some set of distances, so you can better evaluate just how intense the light you would get is. But, few of them do that.


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## Christian_rubilar (Jul 21, 2005)

The “skill” of elodea is to decalcificate the water. It is a plant that does not need light neither Co2 to survive. This is why here, where it is native, it is used in fish aquariums, not planted. If you have a good light, well...


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## Michael (Jul 20, 2010)

I'm with Hoppy on the LED. Check out the one your builder wants to use and make sure it is suitable for plant growth. LEDs have many advantages in closed canopies, the biggest being much less heat. When I was using T5 fluorescents, it was really annoying to change them every 6-12 months as recommended when they are so expensive and not easy to find.


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## cygaj (Jan 30, 2018)

Christian_rubilar said:


> The "skill" of elodea is to decalcificate the water. It is a plant that does not need light neither Co2 to survive. This is why here, where it is native, it is used in fish aquariums, not planted. If you have a good light, well...


Will it be still dangerous under the appropriate amount of light? Or should I take them out?

There is also something about decalcification that I don't understand. I read that it can lead to PH swings. But the name&#8230; so it takes out calcium from water, right? And it's bad if I keep shrimp and snails, right?

I managed to get the forth bulb going with my dad so there is one 24W T5 over my tank for now instead of 4. It should be alright until I instal the new light along with the new cover if I understand correctly. This is how it looks to my (bright) phone camera now that it has three times as little bulbs going on:










I decided to commission a bare bones cover because I think the lights the builder uses might not have the blue and red diodes. There's nothing written about them on a product page or about plants for that matter. I can't also know for sure that it's the same product that this person would instal but that's my best estimate and I don't feel comfortable interrogating him about it until he gives me exact name of the light so I'll leave it at that. I decided that it's gonna be easiest for me to install light myself, having full control over the type so it fits my needs.

So I'm left with the choice: should I go with a single T5HO? (a new one, of appropriate length) Or with LED?

I see the arguments for LED. Do you think they're gonna be enough for my 50cm tall tank? I want a low light but still growable of course. And if so then what kinds of tapes should I use?

I found these for example. It says that diodes are SMD 2835 and it doesn't say how many of them there is but&#8230; this seems to look the same and it says it would have 78 diodes for 80cm tank. I'm wondering if something like that would be enough or should I build my own light?

What I'm trying to find out is how many and what type of diodes would be few enough to be low light but also enough to still grow plants under them, for it to be a working low tech without a need for CO2. Also what would be the good proportion between white, blue, and red diodes. The lamps I linked have ~ 60% white, 25% red, 15% blue. Does it sound right?


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## Christian_rubilar (Jul 21, 2005)

Try to focus.
The elodea does not need Co2 because it takes the carbon from the bicarbonates and this produce a rise in Ph and a down in kH. What happens if you put a lot of light abd Co2? I have no experience, the elodea is native in Argentina and we use it to feed carassius.


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## hoppycalif (Apr 7, 2005)

My LED light is about 60 cm from the substrate, and I get about 40-50 PAR, medium light. Here is a thread about making my light: http://www.aquaticplantcentral.com/.../136594-smd-led-tape-based-light-fixture.html

I'm not suggesting you make your own light, but it isn't all that hard to do. My LEDs are brighter than the ones in that light you linked to, so if it only has one strip of LEDs it isn't likely to be enough light, although it may be. My tank is about 60 cm tall, and the light is about 5 cm above the top of the tank. If the light has two strips of LEDs, I would bet that using two of them would give you about the right amount of light.


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## cygaj (Jan 30, 2018)

hoppycalif said:


> I'm not suggesting you make your own light, but it isn't all that hard to do. My LEDs are brighter than the ones in that light you linked to, so if it only has one strip of LEDs it isn't likely to be enough light, although it may be. My tank is about 60 cm tall, and the light is about 5 cm above the top of the tank. If the light has two strips of LEDs, I would bet that using two of them would give you about the right amount of light.


These lights in the link do actually use two strips. But if you suggest that I should use two of these lamps (four strips?) then you're right I should make my own instead most likely!









Thank you for the link about light making. I don't have a time right this moment to think about the lights (cover ordered, light over tank reduced for now, so emergency over) but I'll try to focus on it on a free day.

And I'm sorry about so many eloda questions. The thing is I'm a absolute chemistry noob and I only can learn as I go. I'll try to give Christian's description more thought and reading up on a free day also.

This is my first aquarium and as much as I've researched there will be always so many things I can only learn about when I get to them.


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## micheljq (Mar 25, 2013)

Hello, it is important to get a pH test and also GH/KH test.

Check for pH swings, verify the pH when the lights lit, and then after the lights are out.

Verify the GH and KH, the KH, is a buffer which protects againts potential dangerous pH 
swings. Elodea has been known to quickly change those parameters under strong light, when photosynthesis is done.

http://www.americanaquariumproducts.com/AquariumKH.html

Michel.


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## hoppycalif (Apr 7, 2005)

Here is a suggestion: It is very hard to guess how much light a LED light is producing. But, you can buy a cheap digital lux meter and use it to measure the light out in the air, at the distance from the light that your substrate will be, and convert the lux reading to PAR units. The lux meters look like:









These are sold at several internet stores, including Ebay, where I was buying them. If you divide the lux reading by 70 you will have a reasonably good estimate of the PAR reading. You need about 30 PAR to have good low light, and about 40-50 to have good medium light.

Just remember that these lux meters are not water resistant, so they only work in the air. There is very little difference in light intensity measured in air and measured at the bottom of an aquarium, so this is worth the effort.


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