JDShort98

Ok, I am new so don't kill me for asking a question that I am sure has been answered here before! I have a 72 gallon Bow front, been up and running for about three months. For the most part all is well.
My set up is river rock for substrate, some very basic, easy to care for live plants, a few pieces of Mopani for decorations, and about 200 pounds of what I call slate, or field rock. The slate is a very pale green color, looks really great in the tank. I have a couple piles, is design so that my fish can swim thru. As far as fish go, I have fresh water fish, fish from our local lake system. I have a Couple Tilapia, a few blue gills, a catfish, a shellcracker, a few crawfish, and a couple warmouth. The tank stays crystal clear thanks to my Marineland c360. The water parameters all check fine, PH stays neutral, no ammonia or nitrites, I change about 20 gallons weekly (fish leave a lot of waste behind) and this keeps my nitrates under 50.
Here is my problem, the slate I love so much, turns brown where ever the light hits. Where they are stacked and the light can't hit, they look fine. It appears to be a brown algae, can be scrubbed off, but my pleco has no interest in it what so ever. I bought some AlgaeFix, but I think will kill my crawfish??? I run the light about 12-14 hours a day, sadly I realized today it is only a single bulb 32 watt light. I am thinking the low level of light is the problem, but the plants do fine. And I have a bubble wand on one end for decoration, and where the bubbles pop and the moisture gets on the glass lid under the light, green algae grows there no problem in a week every time. Please advise!

peanutbowl

jd,
welcome!
probably the most obvious cause of your algae problem is the amount of light you are supplying your tank with. 12 to 14 hours is too much. it seems many people have excelent results with just 8 to 10 hours daily. unfourtunately, i am no expert and this may only chaulk up to being a reletively generic answer.
my advice is this. read the sticky in the general freshwater forum about getting help. it will advise you on information that you should supply to get a more informed answer. also, wade around in the freshwater plants forum. and really dig in the crates on this one. there are tons of information in there regarding finding the proper balance of nutrients to not only allow your plants to flourish but minimize algae growth as well.

good luck!!!
cheers!

__________________
29g High Tech Planted w/ Rainbows, Platies, Cories, and Shrimp
12g freshwater w/ 1 blue paradise gourami

Jay

Hey JDShort...Welcome to the Forum

The brown covering you are describing is most likely Diatoms. Not really an algae but another single cell critter. They are very common in new aquariums, under six months. They form hard shell like coverings from silica in the water column. They are usually short lived and die off as the silica diminishes. New Glass, some substrate gravel and sand etc. can leach silica into the water.

Slate is usually great in an aquarium as long as it does not have feldspar in its composition, which can leach silicates resulting in diatom growth.

IMO & IME it can and will kill everything in your tank.

Jay

JDShort98

Thanks Jay!

I think you are right, I did some reading about these Diatoms you talked about, and most people who have dealt with them also mention the golden color to them, and that is what I have. Not sure to tell if the slate I have has silicates in them, I can only go by what the guy selling the slate told me, that he uses them in his tank too. One thing I did notice, when I added some freshwater salts to the tank, the salts killed the Diatoms where the salt landed.
Anyway, here is my question. I have found in my online searching some people mention using a silicate filter media...I can't seem a place to order it or even read details about it anywhere? Any suggestions?

Thanks Jay!

Jay

Decreasing the light will have no effect on these guys.

A phosphate removing resin pillow will also remove silicates.

So will increasing the size of your water changes for a while.

Jay

peanutbowl

will the "diatoms" respond to light at all? they do seem to place themselves in areas of the tank that recieve light, versus areas that don't. this is true for my tank as well.

__________________
29g High Tech Planted w/ Rainbows, Platies, Cories, and Shrimp
12g freshwater w/ 1 blue paradise gourami

peanutbowl

*DANGER* I'm about to make an assumption. could it be less about the actual light and more of a response to, say, radiant heat from the light? this has me very curious.

__________________
29g High Tech Planted w/ Rainbows, Platies, Cories, and Shrimp
12g freshwater w/ 1 blue paradise gourami

Jay

LoL...

In this discussion, we are talking about fw tanks, and how to control or eliminate diatoms.

Diatoms are ubiquitous in nature, they are present in most fw aquariums, the questions are what triggers the bloom and how do we control them once the bloom has occurred.

Since they can exist in very low light, limiting the photo period will not be effective although I would think a 72 hour complete blackout would do them some damage.

It is really the water parameters that are important. The presence of silicates, as discussed, and the ratio of phosphates/nitrates (I can't remember off the top of my head what that is) will trigger a bloom. If the silicates and nitrogen phosphate levels can be lowered the colony will die out very quickly. Large and frequent water changes over a few weeks should accomplish that. Over feeding will contribute to the NO3/PO4 build up. Remember single cell critters cannot store energy or nutrients like higher plants or fish.

Jay