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Discussion Starter · #1 ·
Hi all,

I'm relatively new to keeping a planted tank. I started my 20 gal high (20x10x18) as a fish only tank about a year ago and have slowly started migrating towards keeping plants as well over the past 3-4 months. It started out OK for a while using the standard light fixture w/ a 15 day aquaglo bulb over some anacharis and hornwort (12 hour photo period). Slow but reliable growth from both but no serious algae.

More recently - about a 2 months ago - I got ambitious and upgraded to an AH Supply 36 watt DIY fixture and added some more plants - a large sword (ozelot, I think - dark brown spotted leaves that become more green over time), a smaller oriental sword, replaced the old anacharis with new (old was starting to look "stumpy", lots of new, but very short growth almost looking like a ball, looking back I assume this was nutrient deficieny as I wasn't fertilizing and I have inert substrate) and corkscrew val. i got rid of the horwort. I also started feritlizing ever week and half to 2 weeks with Terta Plant FloraPride (0-0-3 mix with just Fe and K).

Ever since adding the light and plants I've basically got myself an algae farm. Started out with green spot algae on the glass and the origianal leaves of the ozelot sword. Lately it's become a free for all with black beard algae, thread algae and some sort of reddish/brownish algae. Traveled for Thanksgiving and came back to 6 inch long threads growing off of plants, decoations, and off of the substrate and shorter brownish thread or hair algae completely covering the original val.

I've had some decent plant growth the whole time along (val sent out 2 new sister plants, ozelot is good for at least 1 new leaf a week, same with oriental) but the algae just seems to be outgrowing the plants.

I've listed my setup below. I've spent countless hours pouring over forums and books to educate myself on this, but just can't seem to figure out what is giving the algae such an advantage. I'd like to avoid C02 on this tank (if I can figure this out, I have dreams of a 75 gallon tank that I may go high tech with).

Keep in mind, this started out as a fish only tank.

20 gallon
Filtration: Whisper EX20 HOB, and an undergravel filter
Subtrate: inert aqurium gravel, Seachem FlourishTabs inserted near swords and val
Light: 36 watt compact flourescent AH supply DIY
Temp: 78
ph: 7.6
ammonia:0
nitrite:0
nitrate: 5-10ppm
phosphate:0 - .25 ppm
gh: 10 deg
kh: 3 deg
stock: 2 small angels, 6 neon tetras, 3 chinese algae eaters
photoperiod: 5 hours on, 2 hours off, 5 hours on

20% water changes weekly to every 2 weeks using 1/2 tap water and 1/2 distilled (very hard tap water). API Tap Water Conditioner to remove chloramine.

Fertilize at water changes with Tetra FloraPride (0-0-3 Fe and K only). I'm guessing the hardwater and fishfood are taking care of other nutrient needs.

Is this too much light for a relatively small plant load / no CO2? Would reducing the photo period further help or should I revert to the old 15 watt light if I'm not going to add C02?

What are thoughts on running the HOB carbon filter in a planted tank?

What are thoughts on Fe fertilizing and algae? I've read that Fe excess is a leading cause of algae and the exact opposite, that Fe shortage hurts plants and is the leading cause of algae.


Sorry for the long post. Any insights anyone has would be greatly appreciated. I'm at the end of my rope!
 

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Hi DM, welcome to the Planted Tank, the right place for all algae issues!

What you experienced is an imbalance of light vs nutrients. With your 15W bulb, plants hardly grew, and whatever was in your water provided by fish and fishfood kept them alive.

When you changed your light to a higher intensity 36W bulb, plants got a lot more energy to build up substance, but now the available nutrients ran out, and opportunistic algae moved in.

While adding some Florapride takes care of certain things, it doesn't contain Nitrates or Phosphates (macro nutrients) or CO2, and that seems to be the issue here. Even though you tested for NO3 and found some, I am going out on a limb and say your testkit might show a bit of a false positive. Did you compare it with NO3 free water and see some clear differences?

I would not blame Fe fertilizing... Reducing your photoperiod and/or raising the fixture might or might not reduce the need for additional CO2 injection. Don't be afraid of CO2, and a DIY setup is very easy to do and sort of fun for a while.

Definitely look into NO3 and PO4, and keep in mind that more is often not better, but if something is missing completely plants are at a disadvantage.

Don't expect instant results either, once you fix a few things give it several weeks to show the changes.
 

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Discussion Starter · #4 ·
Thank you for the welcome, useful info, and encouragement.

I've tried the Nitrate test kit side by side between tank water and distilled water in the past and noted significant color differences, so I'm pretty positive that it's not a false positive. I'll check again. But I think the Phosphate test on the tank water did look pretty close to the distilled test. I guess I'd read that high Phosphates were bad and assumed that meant 0 phosphates were good. I'll start supplementing Phosphates. Is there an ideal Phosphate level?

I guess I've been holding off on the CO2 addition because it didn't seem 'natural'. Nothing I've read ever mentioned indigenous populations of 2 liter bottles filled with yeast and sugar. But I guess there are natural processes happening in most streams/lakes that achieve the same effect?

It was kind of exciting to come home with $10 worth of stuff and see bubbles an hour later. Looking forward to seeing the results over time. I guess this will make the Angels happy too as it should bring the pH down a bit.

Thanks again.
 

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You are a good observer... rarely there are sugar/yeast bottles in nature. :biggrin:
However, it is also difficult to find a piece of stream or lake that you would really want to cut out and transplant into a show tank. Ten or twenty gallons of water in a glass box are not very "natural" to start with. But that's a completely different discussion.

CO2 will make it easier to get that a lush variety of plants in our little boxes.

It won't make your Angels happy due to lower pH... if you are thinking "soft water", that's more of a hardness/TDS thing which doesn't change when injecting CO2. On the other hand, added CO2 will make plants grow faster, and in the process produce more oxygen, which indeed might be appreciated by your fish.

And hopefully, with some time you get the algae under control too.

Too much PO4 isn't good, especially when you are already dealing with algae. But 0.5-1ppm will help your plants grow to full potential. 0 ppm is no good... it's considered a macro nutrient, and just as essential as all the other nutrients.
 
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