# Please help me grow plants



## mdog (Dec 10, 2002)

I have one tank that doesn't grow plants and one that grows them like weeds. My daughters 29 gal. grows plants so lush she has to thin them every couple of weeks. I put these same plants in my 75 and they slowly die - every time. They get covered with a slimy green algae and then decline and die. I'm not sure if they die from the algae or get the algae because they are dying. Both tanks have same water, and roughly the same temp 77 - 79 F. The 29 has 1 20W bulb - pretty low light but it works. The light is on whenever my daughter thinks of it, probably an average of 7-8 hours. The 75 has 3 40W bulbs. This is on a timer and it gets about 12 hrs. Also the 75 gets algae on the glass every 5-6 days and needs cleaning. It also gets a coating on the substrate and wood, rocks, etc. The 29 hardly ever needs the glass cleaned. Could I have too much light on the 75? Hard to imagine plants dying from too much light. Any ideas? Thanks


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## Evan805 (Apr 19, 2010)

I have heard that if you have too much light you _need_ Co2.

I could be wrong or maybe misunderstood.


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## mdog (Dec 10, 2002)

I guess the easiest thing would be to cut back the hours of light and see if that helps but it just seems wrong.


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## DJRansome (Oct 29, 2005)

Definitely too many hours on the 75G. But also possibly the nutrient levels are different in the two tanks. What is the measurement of nitrate and phosphate in the two tanks?


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## alexlee04 (Jul 19, 2009)

It sounds like you have a cyanobacteria (blue-green algae) outbreak in your 75gal tank. This comes from an imbalance in nutrients and too much light. More phosphate and less nitrate you get blue-green algae. More nitrate less phosphate you get green hair algae. One makes your tank look natural and healthy and the other will kill any plant in your tank.

I'm sure there are other ways to get a blue-green algae outbreak so still test your tank for nitrate and phosphate and let us know what you get.

*edit* I found the thread where I got my info. Here it is...
http://www.cichlid-forum.com/phpBB/viewtopic.php?t=208909


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## mdog (Dec 10, 2002)

Thanks for the good info. I will test for nitrate but have never tested for phosphate - not in the common test kits I guess. So, what do you do if there is too much phosphate? I wonder why the two tanks would have different nutrient levels if that is the case.


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## alexlee04 (Jul 19, 2009)

My guess would be that if the 29g tank has plants growing like crazy then any nutrient that gets produced by the breakdown of organic matter gets consumed by the plants immediately for new growth. So I bet a test of your 29g tank would show very low nitrates and phosphates.

For me I got a outbreak of blue-green algae after adding shells to a shelly tank that still had some snail in them. After that it seemed like it jumped to the rest of my tanks. Now its been a real challenge to get rid of it.


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## mdog (Dec 10, 2002)

So is the answer to the original question that the algae is probably killing the plants? If so, maybe just cutting back on the hours of light might help, right? Reading through some of the info makes me realize I don't want to start messing with the water. My fish do great with no chemicals other than de-chlorinator. I like to keep it simple. Thanks.


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## Number6 (Mar 13, 2003)

*mdog*
I've run tanks with 12 hours and even more than that without issue so yes, you might have too much light but I can't say that without much more info.

I'm going to think out loud and please don't take anything the wrong way... I am simply trying to get as much info out as fast as possible. :thumb:

The 29g tank likely works as the bulb is close to the plants and the tank is packed... algae has to compete against an army. If it has a good reflector, even better... So how does your 75g really compare?

Ok, step 1... stop thinking about wattage. Plants don't care about power consumption, only your spouse does at bill paying time. All wattage is good for is a ballpark to start guessing your light levels from. 
So... 120W of light... reflector? If bulbs are tightly packed in, flat back metal reflector, assume around a 35% light loss. If no reflector, assume ~50% light loss. If parabolic polished aluminum with a reflector per bulb, ~10% loss. 
What are you at now?

Now realize that the tank is taller... it's also larger, so you cannot ignore water flow. 
Now, how much real estate do you plant? and do you move cuttings? baby plants? It can often be smarter to leave baby plants in your smaller tank and transplant the parent plants. Are you planting at least 60% of the tank? if not, then the cyano gets to reign unchecked IMHO and IME.

Now... light duration. Is 12 hours too much? many plants can use more... elodea can, but do you have true aquatic plants? simple plants? marsh plants fully submerged? All of that matters. What do you think the CO2 level is at in each aquarium?

What I would do in your shoes is plant denser on your next attempt, use more parent plants, buy a timer that allows for two photo periods and insert a 4 hour break midday, add more circulation to get rid of the cyano (maybe even an anti-biotic treatment if you have to) and make sure all the light you produce is getting to the leaves of plants... ahsupply.com sells great reflectors!

I hope that helps somewhat...


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## fmueller (Jan 11, 2004)

I am assuming these are low tech planted tanks - no CO2, no extra fertilizers, just fish poop. I've run a similar 29G for some years, and it had good plant growth. I've run a 75G with one T8 tube, and plant growth was terrible - even Java moss would die. I then upgraded to a cheap double strip T8 shoplight, and the tank has better plant growth than the 29G. All my lights are on for about 8h. As a rule of thumb, plants can make use of light for 8h per day. Algae can make use of light 24x7. With the lights on for 12h, you put the plants at a disadvantage over algae. To make use of the extra light from a third light strip over the 75G, the plants would probably need CO2 and fertilizers. That light will also encourage more algae. Once the algae start taking off, they cover the plants, so even less light gets to the plants, which will grow slower, and take up less nutrients that will also benefit the algae. All this seems in perfect agreement with your observations.

My suggested solution would be to take one light tube off the 75G, and reduce the light in that tank to 8h - maybe 9 or 10 as a compromise if you spend more time in the room and want to see the setup. I'd be very surprised if that didn't solve the problem in the 75G.

Frank


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## mdog (Dec 10, 2002)

Great information! Thanks for the replies. The inside of my double light strip is shiny aluminum, like a mirror. I guess that's the reflector mentioned. I'll leave this one on and remove the single light strip. If I go to 2 light periods with 4 hours off in between, how long should the 2 be? I'll also plant thicker. I haven't planted nearly 60% - usually just 2 good sized clumps. 
So, I plan on doung a good water change and cleaning and then reducing the light and planting again.
Should I wait to plant until the light has been reduced for a while so the algae dies, or can I go ahead and plant as soon as the light is adjusted and tank is cleaned?


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## kmuda (Nov 27, 2009)

I agree with everything stated prior.

I have had a similiar experience. Plants growing great in a 29gallon and getting covered with the slimy green in a 55. In my instance, the 55 is getting more light (I intentionally cranked up the lighting) so I ran into the "more light, not enough CO2 issue".

Resolution to my issue was pretty simple, I started dosing that tank with SeaChem Excel, an alternative carbon source (alternative to CO2 supplementation). My existing plants had reached a point of no return, so I removed them, scrubbed the tank down, replanted, and dosed with SeaChem Excel at one capful per day. Plants are now doing great.


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## Number6 (Mar 13, 2003)

*mdog*
If you combine fmueller's advice and mine, two 4 hour photo periods could be a great start. You can slowly increase the lengths if you notice plant growth and algae recession.

For the Cyano that is there now, mechanically remove as much as possible and add another powerhead like a koralia. It will increase the flow and the cyano will struggle.


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## mdog (Dec 10, 2002)

O.K. I have adjusted the lighting as suggested, cleaned the tank well and did a good sized water change. In a few days I will re-plant with plants from the 29 that need to be thinned again. I've never used power heads but have one I bought years ago and never used. It's a Maxi-Jet ph MP 900. I have two filters on the tank now - 1 cannister and 1 good sized external hang on back- and it seems like there is enough water movement. I guess I just resist adding more stuff in the tank if I don't need to. Any thoughts on that?


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## Number6 (Mar 13, 2003)

In my experience, cyano can only really take off as a coating on the plants when there is slow moving water down at the bottom of the tank. Koralias make plenty of water movement without being a jet of water, so that is my recommendation. They look good as well! IMO of course. :thumb:


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## middlearth (Dec 30, 2009)

So, if the Koralia increases water movement, will that drive off CO2, or does that just happen if there is visible turbulence on the surface?


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## Number6 (Mar 13, 2003)

*middlearth*
gone are the days when we tried to minimize water movement to allow a CO2 build up... if you want additional CO2 you add it via pressurized CO2 or a DIY CO2 reactor. If you are not adding CO2, then you'll want to add it via the surface of the water with PLENTY of water movement...

I hope that helps!


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## westcoastkid (May 24, 2010)

What is your substrait like? Alot of your plants nutriet uptake is from the roots and if theres nothing for them to eat they will die.


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## Maccgyver (Jun 6, 2010)

Your lighting is still within the realm of what is usually recommended, 2 watts per gallon. You are at 1.6 per gallon with your 3 40 watts. I would say reduce the amount of time the light is on a bit first and see what happens after you clean your tank and then go from there.


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