My rock wall is a grassy knoll

[Emma1234]

Hi. I have a fifty-gallon tank that I set up a few years ago. I wanted to have a rock wall with coralline algae covering the rocks. I built my rock wall following instructions on the internet for DIY rocks. I made three large rocks to make up the wall. The largest of the three rocks weighs about 30 lbs and the smallest is about 15. I attached a photo of my tank.



My problem is that I haven't got much coralline algae, only a lot of green algae in the display tank. I do have quite a bit of coralline algae in the sump.

I have protein-skimmer, I use a Chemi-pure product to remove phosphate. I have three powerheads, one behind the rock wall and two in front. One on each sides of the tank. I have a 20 gallon sump.

Water parameters (Hanna and Siefert checkers). ALK 177, Phosphate .036, Ca 436 and Mg 1560

I'm wondering why I haven't got any coralline algae in the DT. I wonder if the rocks are too big and dense. Or if something else is causeing the problem. Should I try to break up these big rocks? Or should I take them out and start over with smaller rocks? Or just spread the rocks out as much as possible to allow more flow. Or would adding more power heads help or would too much flow be bad for the corals? I'm looking for any ideas and advice you may have as to how to get these rocks covered in coralline. Thanks in advance.

2 clown fish, urchin, clean up crew. Soft corals (star polyps, leathers, mushrooms). LPS, Hammer (not doing well). Candy cane (doing very well, growing).

 

[Sk8r]

can you translate that alk reading to the dkh scale?

 

[Emma1234]

I believe 177ppm converts to 9.895 dKH

 

[Raintree]

Assuming your parameters are/have been stable, the only thing i can think of that might limit coralline growth is light. What lights do you have on the tank?


Do you have any coralline growing in the DT at all? you could scrape some from the sump to help it spread

 

[Emma1234]

I have one Current USA Orbit Marine LED Saltwater Reef Lighting System:
48 Dual Daylight/48 Dual Actinic LEDs, 96 LEDs Total

And one addition Actinic 36 inch LED strip, not sure how many total LEDs are in this in the Actinic strip. I did a rough count and it looks like there are about 200 small blue LED lights in this strip.

I did scrape some of the coralline from the sump. There is very little coralline in the DT. On the overflow, and powerheads. But mostly green algae dominated for years.

I do weekly water changes with RO/DI water.

 

[vhuang168]

But mostly green algae dominated for

I think that is the issue. If you have green algae covering the rock, there is no where for the coralline to grow on. Any growth will be smothered by the green algae.

Get that in check and coralline should start encrusting.



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[Raintree]

I'm surprised that urchin hasn't cleaned up the algae. What kind of urchin is it?



Those lights are very weak by the way. If you can upgrade your lighting, it might help

 

[Green Chromis]

Hi. I have a fifty-gallon tank that I set up a few years ago. I wanted to have a rock wall with coralline algae covering the rocks. I built my rock wall following instructions on the internet for DIY rocks. I made three large rocks to make up the wall. The largest of the three rocks weighs about 30 lbs and the smallest is about 15. I attached a photo of my tank.

View attachment 361096

My problem is that I haven't got much coralline algae, only a lot of green algae in the display tank. I do have quite a bit of coralline algae in the sump.

I have protein-skimmer, I use a Chemi-pure product to remove phosphate. I have three powerheads, one behind the rock wall and two in front. One on each sides of the tank. I have a 20 gallon sump.

Water parameters (Hanna and Siefert checkers). ALK 177, Phosphate .036, Ca 436 and Mg 1560

I'm wondering why I haven't got any coralline algae in the DT. I wonder if the rocks are too big and dense. Or if something else is causeing the problem. Should I try to break up these big rocks? Or should I take them out and start over with smaller rocks? Or just spread the rocks out as much as possible to allow more flow. Or would adding more power heads help or would too much flow be bad for the corals? I'm looking for any ideas and advice you may have as to how to get these rocks covered in coralline. Thanks in advance.

2 clown fish, urchin, clean up crew. Soft corals (star polyps, leathers, mushrooms). LPS, Hammer (not doing well). Candy cane (doing very well, growing).

:fish1: Hi, you made your own rocks, what did you use to make the rocks? By looking at your picture it looks like your rocks are the only thing with algae growing on them, maybe the material you used is leaching PO4 into your aquarium, as I see your PO4 is a little high. :fish1:

 

[Emma1234]

I'm surprised that urchin hasn't cleaned up the algae. What kind of urchin is it?

Those lights are very weak by the way. If you can upgrade your lighting, it might help

The urchin is a Longspine Urchin, Blue Spot. I believe it is eating quite a bit. I took some of the macro algae from my sump and put it in my display tank to see if that would help grow coralline algae since I have coralline in the sump. But I think that caused the green algae to grow faster in the DT, at least it looked that way. The sea urchine parked himself (herself?) on the macro algae and, I assume, was feasting on it. I removed the macro algae from the DT after just a couple days.

When I set up the tanks selecting the lights was one of the most difficult choices. I ended up going with what was available from the LFS. I need to do more research. But....if there is a lighting system that is clearly superior to what I have I would appreciate the recommendation.

Hi, you made your own rocks, what did you use to make the rocks? By looking at your picture it looks like your rocks are the only thing with algae growing on them, maybe the material you used is leaching PO4 into your aquarium, as I see your PO4 is a little high.

I used white Portland cement, crushed coral and rock salt. I don't remember what the proportions were but I followed a recipe I found online.

You are correct. The only place where there is green algae is on the DIY rocks. If the rocks are leaching PO4 is there anything that can be done besides replacing the rocks?

 

[Emma1234]

One other point of information about my problem. I have a Hanna Phosphorus ULR checker. After multiplying the reading by 3 to convert from phosphorus to phosphate and converting the number from PPB to PPM by dividing the result by 1000, I have taken 4 readings the past couple of days with the following results: .021, .036, .108 and .015, ppm. These are frustratingly different. Is this a sign that there is a problem with the phosphates? Or is it more likely that the Hanna checker is not providing accurate results, either due to operator error or the checker not being reliable? I was very careful taking the readings and the .108 and .015 were taken within an hour of one another. Any thoughts?

 

[vhuang168]

Is the reagent expired?


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[Emma1234]

The reagent hasn't expired yet. The expiration date is 5/2018.

 

[Walla2GSP]

What are your nitrates and how much are you feeding? I use only DIY rock and my coraline is everywhere. I would suggest stopping with the chemi-pure, get another phosphate test if you are unsure yours is reliable, and test nitrates and phosphates twice a day to see if the numbers rise quickly or slowly. Personally, I just brought a tank out of a 2 year long neglect period and my nitrates and phosphates only rise slightly over a week, so if you are having to deal with them daily something is putting nitrates and phosphates in your water column or you are over feeding the tank and coraline isn't going to growth in those conditions. IMO

 

[mpierce]

Your urchin probably munches all your coralline algae, mine loves it.

 

[SAO]

I have never been a fan of DIY rock for the simple fact that I has seen it personally leach phosphates into the water over time. I would say the algae growth is from just that.

 

[Emma1234]

I'm not completely confident in my Hanna Checker since the results can vary significantly in a short period of time. I checked for nitrates after I read Walla2GSP's reply. I have a Salifert test kit for nitrate. The result was 1 ppm, which I've read isn't high but I don't feel confident in this test result or the test kits in general.

I think that I have a phosphate issue based on the green algae in the tank. Based on the information in the posts I think it is either that the DYI are leaching phosphates or I might have had too many dead spots in the tank.

I did a water change today, moved the rocks, cleaned thoroughly where the rocks were sitting and relocate the rocks to allow for easier flow of water between the rocks. Here are pics showing before I reorganized the rocks and after.

View attachment 361167



I will see if the change in the arrangement of the rocks makes a difference in the amount of green algae and the growth of coralline algae. Hopefully, the better water flow will help.

One other possibility (credit mpierce post) is that my urchin is eating the coralline algae. If that's why I don't have coralline algae I'm fine with it. I like my urchin. But the urchin can't be why I have green algae. So in a couple of weeks if I don't have green algae or coralline algae then I might blame my urchin for the lack of coralline algae.

But, if in a couple of weeks I still have green algae I will believe that my rocks are leaching phosphates and I will have to remove them.

I'll post the results.

Thanks for your input and please let me know if you have any ideas!

 

[SFish]

One other point of information about my problem. I have a Hanna Phosphorus ULR checker. After multiplying the reading by 3 to convert from phosphorus to phosphate and converting the number from PPB to PPM by dividing the result by 1000, I have taken 4 readings the past couple of days with the following results: .021, .036, .108 and .015, ppm. These are frustratingly different. Is this a sign that there is a problem with the phosphates? Or is it more likely that the Hanna checker is not providing accurate results, either due to operator error or the checker not being reliable? I was very careful taking the readings and the .108 and .015 were taken within an hour of one another. Any thoughts?

The Hanna checker should be fairly accurate. Maybe try 3 or 4 tests in a row. Looking at your numbers the 0.108 looks like a bad test. Your precision doesn't look that great. Do they make standards fot PO4? If so I would pick up some.

 

[homer1475]

Algae is the number one reason you don't have any corraline on your rocks. Coralline will not grow over the top of algae. Get your rocks clean, keep the algae in check, keep your parameters stable and the coralline will follow.