High Light vs Photoperiod vs distance (PAR)
How do I get my lush hairgrass back?
So I've been running my tank for about 8 months:
I had an outbreak of hair algae when I first set up and realized my lights were waaaay too close to the surface. I hiked them up and now they are 33 inches from the substrate and 16 inches from the surface of the water. I also did a blackout that wiped out the algae (along with my tiger lotuses)
I then got the ferts wrong and had a nice outbreak of BBA which was a pain to get rid of, but is nearly non existent after a month thanks to Excel and regular water changes.
I have 4x 39W T5 HO bulbs running in two separate banks.
I currently run one bank of light for a total of 6 hours. (14:00-20:00).
I run the second bank of light for 5 hours (17:00-22:00).
78W for 8 hours total, of which 156W for 3 hours (when they overlap 17:00 - 20:00).
I run pressurized CO2, and ferts - everything grows really well - The reds are starting to pop on the plants that are near the surface and staurogyne repens is growing like a weed but the hairgrass...
The hairgrass is alive, but quite thin compared to when the light was closer (When I set up the tank).
I do not want to have an algae outbreak again so I'm toying with dropping the light an inch to increase the PAR value at the substrate surface, alternatively, I can increase the photo period or the amount of light
I've read that dwarf hairgrass likes 2WPG or more. That being said, I know to focus on PAR vs WPG as a measure of effective light.
So what's the recommendation? I won't do any drastic changes - one nudge and wait, another nudge and wait...
Here's what it looked like at day 31:
Here's a pic now:
lifeless hairgrass in the front right and middle.
Nice looking tank, is that A. Viejita on the right side on D31-what strain is that?
I'm no expert when it comes to ferts, light and CO2, but in my opinion.., Looking at your before and after, I think it's safe to say you don't have enough light for a carpeting plant like that. Also, I would not be fond of the amount of stray light you are getting with your light so high up. I mean how can you enjoy your tank with 4 bulbs of T5 HO blasting you in the eyes!
My suggesting: move it back close enough to the tank where viewing is enjoyable, and get some floaters like frogbit or dwarf water lettuce to shade out some of the light. Also keep the photoperiod to 8 hours or less. In my mind when I think of algae and light, the longer the photoperiod the better the algae will do. I'd rather have high lighting for a short time, than weaker lighting over a longer period. Your plants will appreciate the high light, they are more efficient than the algae and only need a few hours of it a day to thrive. Furthermore, I don't see any harm in having a few photoperiods a day, and I suspect it would benefit your plants, I understand your trying to replicate nature, but there is lots of algae out in nature too and lets face the facts, most natural systems don't have injected CO2! I set my photoperiod to be on only when I'm going to home to enjoy it, plus I'd just have all 4 bulbs on, I don't think the plants really care if it ramps up from 2 to 4 bulbs.
Light causes algae, C02 grows plants! 2 x T5 is more than adequate to get a lush growth of any plant at that depth of water,
You need to get more gas down to the substrate.
I was too chicken to move the lights lower so just increased the photoperiod by half an hour every couple weeks. My hairgrass, Blyxa and P. Kawagoeanum responded beautifully to an 8 hour photoperiod. Your choice I think.
Thanks for all the input!
The Apisto is sold as a Viejita "red neck", don't laugh :) I've been corrected on the Apisto Forums (yes there is a forum for everything under the sun) that it is a Apisto Macmasteri - At least that's what they call in in Europe. I purchased it from WetSpot and I would highly recommend them - great service and fantastic fish.
I have it at 8 hours with a 3 hour burst - that sounds like good medium/high light when I check the PAR guide on the forums that Hoppy posted a while back.
I may drop the light an inch and keep vigil for algae...
I thought I could add an extra hour to the quad lamp burst (156W) to make it 4 hours instead of 3. I am cautious that dropping the light an inch increases the PAR for an entire 8 hours instead of doubling the PAR for 1 hour. It seems like a larger swing.
Any ideas? :)
What specific light fixture or fixtures are you using. Since my original charts of PAR vs distance were posted here I have seen a lot more data from a lot of different lights, and even more manufacturers are selling T5HO lights. So, I have posted a different set of charts at http://www.plantedtank.net/forums/sh...d.php?t=184368 The PAR you get depends on both the reflectors and the ballasts, and different manufacturers use different quality parts of both kinds.
I haven't tried hairgrass yet, at least not long enough to learn much about it. So, I can only go by what is posted here in guessing what it requires.
Since that tank is 18 inches front to back depth a single light fixture with closely spaced bulbs isn't likely to give uniform lighting over the whole substrate. But, if the light is high enough above the tank, it will give relatively uniform lighting. So, I suggest working with only two bulbs, closely spaced, if you have the light high above the tank, but using 2 widely spaced bulbs if the light is right at the top of the tank. But, that changes if you have one of the inefficient T5HO lights.
Hoppy, Thanks for responding :)
I just looked at the new charts and wow, there's a lot more to consider. My unit's not listed there and I'm not sure what the reflectors look like on those units.
I'm using an Aquaticlife 4x36" T5HO unit: http://www.aquaticlife.com/products/286 It has worked reliably and their customer service is pretty good, btw.
You can see the PAR performance in their user manual (Page 4/5): http://www.aquaticlife.com/sites/def...ets/420036.pdf
I've got 2 of the original Aquaticlife 6000K bulbs (8 months old) and 2 Zoo Med Ultra Sun Trichromatic Super Daylight Bulbs 6500K (http://www.amazon.com/gp/product/B00...ms_ohs_product). (7 months old)
The reflectors are 1/2 parabolic but each bulb has a reflector.
The unit is 9" across, the bulbs are evenly spaced and 8" apart.
I'm starting to think to try this:
Thank you for posting that Aquaticlife manual. I added the PAR data to http://www.plantedtank.net/forums/sh...d.php?t=184368 along with one of your photos of the reflectors.
You can see, from that chart, that at 33" you are getting about 70 micromols of PAR, which is more than enough light to grow hairgrass. If you were to use just an adjacent pair of bulbs you would get about half of that, or 35 micromols, which might be too little light. But, lower the light to about 22-24 inches from the substrate and you should have about 45-50 micromols of PAR at the substrate from the two bulbs. That is plenty of light for hairgrass, and based on the charts in the manual, the light would be adequately uniform over the whole substrate.
I suspect your problem is a CO2 problem. Once you have enough light, and dose fertilizers per an EI method, 90% of the problems you will run into are CO2 problems. I suggest:
1. Make sure you have good water surface ripple over the whole surface. No splashing, but good rippling. This keeps the water oxygenated so the fish can live with high CO2.
2. Make sure you have very good water circulation in the tank, with all leaves on all plants swaying in the current. This gets CO2 rich water to all plants.
3. Increase the CO2 bubble rate just a tiny bit. Watch the fish for distress, and the plants, looking for improvements in their health and growth rate. If the fish aren't distressed, repeat this step about every 3-5 days, until the fish aren't happy - then drop the rate to the last one where they were "happy". Or, repeat until the plants are growing in obvious good health and at a good rate. It may take a week at each bubble rate to do this well.
If you want to do a "noon burst" go ahead, but I think it is better to eliminate that while adjusting the CO2 to an optimum bubble rate.
Just to confirm: With two bulbs I'm only giving the substrate ~ 35 micromoles of light, the noon burst is pushing it to ~70 micromoles for 3 hours.
Dropping the light from 33 to 24 inches is a bit drastic, can I do it gradually? I am weary of large changes to CO2 and light - from experience changes to light especially have caused algae outbreaks in the past.
I'm dosing CO2 through an inline diffuser at 2-3bps - for what it's worth, the drop checker is a light green - though I know that's an estimate, etc. I'll increase that by 1bps and wait.
I'll increase the flow - I have a Hydor Koralia pump that runs at night to ripple the surface for flow. I'll adjust the timer so it runs all day.
Could I just gradually increase the light so I have 4 banks on for 8 hours and keep the 70 micromoles at the substrate?
BTW Tall tanks are challenging, because you generally don't have as much plant mass (small footprint) but you need a pretty strong light to reach the bottom.
I am not a particularly active member on this forum mainly because I am English & post on the English forums but I do find it interesting how you guys pay so much attention to light as there is a very different perspective from where I come from ...
We believe you don't need to use high light because you are enriching your tank with CO2 and in fact, as we try to point out repeatedly, enriching with CO2 actually allows you to use LESS light, the more C02 the less light required & therefor less algae That's how amazing CO2 is!
Here is a nice long read .... http://www.tropica.com/en/tropica-ab...and-light.aspx
Very true but I didn't change the fertilizing or the CO2 and with a longer lighting period my plants perked up. Not talking about a minor change. The Kawagoeanum went from 3" leaves and 6" of healthy stem to 4" leaves with 18" of healthy stem. The hairgrass stand thickened within 2 weeks and was 6" tall when I pulled it out. My hairgrass grows tall when light is low, I still had quite low light. There is a minimum length of day for a given system and I was below that point.
70 micromols of PAR isn't extremely high light, so you can use that continuously if you want to treat the tank as a high light tank. That means you absolutely need to keep the water well oxygenated so you can jack up the CO2 concentration to match the plants carbon demands at the fast growth rate that high light causes. To get that CO2 to the substrate level for the hair grass you also have to make sure the grass is waving in the current, demonstrating that it gets "fresh" water continuously. And, you have to be very conscientious about doing tank and filter maintenance, to avoid causing algae with the buildup of organic debris. Then you need to adjust the CO2 bubble rate upwards just a little bit, every few days, while keeping watch on your fish, and observing the plants to see what effect the increases are having. Do this until you get good growth, and until the last increase didn't improve the growth. Finally, if you do start getting BBA, remove it, kill it, immediately or you will soon have a black carpet. If you enjoy all of that work, you will also enjoy the rewards of having a good high light tank.
Here is a nice example of a 100cm tank lit by two T5s approx 40cm above the water, light duration is 6 hours a day.
The tank belongs to Mark Evans and just made Rank 137 IAPLC entry.
We have lots of similar tanks on our forum using 2 x T5 or LED..
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