Plant Only tank question

[creighton]

I have a 20 gal with 55w 6700K AH supply lights and injected co2 with Eco-complete substrate. I'm just keeping fast growing stem plants along with microsword and hairgrass. I'm dosing adding NPK 3 times a week at N=30ppm P=2ppm K=25ppm and CSM+B with Fe at .5ppm. No fish only plants.

My question is about the co2. I don't have a reactor I just run it straight into the in take of my fluval canister. I have the bubbles coming from the regulator going at about 4-5 bps. The filter burps co2 every so often but I think I have sufficient amount of co2 dissolving into the water. Assuming that I do have at least 30ppm or possibly more of co2. Could too much co2 cause algae? I'm having a problem with BGA. It's invading the microsword the worst.

thanks

[VaughnH]

Blue green algae is usually a sign of low nitrate concentration and high light intensity. I suspect your plants are growing rapidly with that much light and plenty of CO2, so that may mean you need to dose more nitrate and phosphate. You could try increasing all dosing to 1 1/2 X the EI amounts for a few weeks to see if that does any good.

[Tom Barr]

You can run pretty juicy, as long as plants are non limited, whether you have 30 or 40 or 60 ppm of CO2 will not matter much, still, have a good sized filter and current, do large water changes often etc

Regards,
Tom Barr

[creighton]

Thanks! I'll try smashing up the nutrient levels.

So another question... I have the ability to run one more 55w 6700K. I've tried it before and had explosive growth, but sometimes explosive algae. I don't really need it, but I bought it and its just sitting there all lonely and cold...

[Carissa]

If you already have an algae problem more light will = more algae for sure.....once you get over 3 - 4 wpg max another light usually just turns into an algae feeding device....especially bga in my experience...

[aquabillpers]

Blue green algae is usually a sign of low nitrate concentration and high light intensity. I suspect your plants are growing rapidly with that much light and plenty of CO2, so that may mean you need to dose more nitrate and phosphate. You could try increasing all dosing to 1 1/2 X the EI amounts for a few weeks to see if that does any good.

I have non-injected-CO2, 2 WPG tanks with soil substrates. When I set up a new tank, half the time I get a BGA outbreak in the first 3 weeks, It is easily controlled. Nitrates are always where they should be.

I think in that environment BGA occurs because the plants take a while to start using the available nutrients, while the BGA is always there, waiting.

Bill

[Tom Barr]

Careful with light, patience is a virtue, let things grow slowly, things that happen fast in tanks= generally bad.

Regards,
Tom Barr

[Carissa]

Couldn't it be excessive ammonia leaching from the soil causing the bga outbreaks? Then once the plants get going, they start sucking it up and it goes away.

[creighton]

Possibly. The Eco-Complete has been in use for a year or so. The plants are doing well since in increased the nutrient levels to 1 1/2 the EI levels. Its kinda scary looking at the bubble counter. If it had any fauna they would surely be dead. I kinda want to add some RCS just so something would be moving in there, but I'm weary to do so .

[creighton]

I have Stargrass, Didiplis diandra, R. Macrandra, P. Stellatus narrow leaf, and needle leaf ludwigia. The needle leaf ludwigia is not growing nearly as fast as the rest of the stem plants. In fact, its barely growing at all. I upped the nutrients so I don't think I have a difficiency and CO2 is off the charts. Could it be that the Needle leaf ludwigia is being out competed for the nutrients it needs? One thing about the P. Stellatus and N.L. Ludwigia is that they are much shorter than the Stargrass, D. Diandra, and R. Macrandra, but they are still getting adequate light.