Could my high iron substrate be causing my brown algae?

[eddie6775]

Hi every one, After months of scratching my head as to why my tank keeps getting diatoms I realized that it usually comes back with a vengeance after vacuuming the gravel. The tank started out with high iron substrate below gravel and of-course, not knowing any better mixed the stuff up pretty good from cleaning up after a melted anacharis plant. I'm wondering if I should consider covering it back up with more gravel or sand. Am I onto something? Here are my parameters in case there's something else I'm missing:

20 Tall, with 2 watts per gallon t8 plant and aquarium lighting on a kitchen timer 8 hrs a day, high iron sub, All of my water tests are consistent (I use the test kit from Pet-smart) and all of the levels are always spot on where the kit says they should be. I do 40% weekly water changes and diy co2 recharged every third week.

The tank is about 75% stocked with fish (as per an on-line aquarium calculator I was directed to (????) and rite now the tank is lightly planted as the algae is winning.

I hope I gave the rite info for some one to help!

[Kudaria]

Have you tried getting a water sample right after you stir up the gravel and testing it? My plants deplete the water of any iron I add within 24 hours to the point I don't want to bleed in the water lest they morph into Seymour so I suspect there isn't as much iron left in your substrate as you might think.

Given this wiki information on the species - Diatoms are a widespread group and can be found in the oceans, in freshwater, in soils and on damp surfaces. Most live pelagically in open water, although some live as surface films at the water-sediment interface (benthic). As their relatively dense cell walls cause them to readily sink, planktonic forms in open water usually rely on turbulent mixing of the upper layers by the wind to keep them suspended in sunlit surface waters.

I suspect what you are actually doing is stirring up the diatom layer upon your substrate and redistributing them upon your plants.

[eddie6775]

Originally Posted by Kudaria

Have you tried getting a water sample right after you stir up the gravel and testing it? My plants deplete the water of any iron I add within 24 hours to the point I don't want to bleed in the water lest they morph into Seymour so I suspect there isn't as much iron left in your substrate as you might think.

Given this wiki information on the species - Diatoms are a widespread group and can be found in the oceans, in freshwater, in soils and on damp surfaces. Most live pelagically in open water, although some live as surface films at the water-sediment interface (benthic). As their relatively dense cell walls cause them to readily sink, planktonic forms in open water usually rely on turbulent mixing of the upper layers by the wind to keep them suspended in sunlit surface waters.

I suspect what you are actually doing is stirring up the diatom layer upon your substrate and redistributing them upon your plants.

That makes sense; so it might be a good idea to just do 'just water' changes for a while instead of attacking the substrate? I'll try it. My ghost shrimp have been doing a good job cleaning up the ground since I rescued them from the store anyway; It's worth a try! Is there such a thing as cleaning too aggressively? ...And no, I usually test before hand...Hmmm.

[Kudaria]

Umm I'm not sure if that is an answer or not as it might lead to other issues with decayed food and plant debris. I'm not sure what the answer to your problem is other than I doubt its iron coming from your substrate.

Perhaps someone with more experience in dealing with brown algae might chime in and give you some suggestions.

[eddie6775]

Oh yeah,.. I do plan on picking up the loose stuff still, but I'm thinking digging all the way down might be stirring too much up. That being said, The topic is still up and I'm absolutely open to suggestions. I get what your saying though.

[lochaber]

I'm curious about this as well. From what I remember, available iron is the biggest limiting factor for oceanic algae. (hence all the geo-engineering 'solutions' to dump iron filings in the ocean to promote algae growth to increase CO2 sequestration...)

I believe Walstad also mentioned something in her book about iron being limiting for algae in aquariums...

Ok, I just checked,and yeah:

Thus, I sometimes have problems with algae after setting up a tank with garden soil, because consideragle iron is released into the water during the first tow months (see page 131). Only after the soil has 'settled down', does the iron release stop and algal problems diminish.

Walstad, Diana. (2003) Ecology of the Planted Aquarium. Chapel Hill, North Carolina: Echinodorus Publishing.

Sounds pretty similar to what she's talking about. I'm beginning to wonder if some of the warning against metals is more about algae control then toxicity.