Algae vs Coraline - What's the difference?

[lazarus]

My tank is > 5 yrs old and I have never developed that layer of coraline growth on the back glass. Until recently, i did not really care, but the algae growth is now getting on my nerves. I have to scrap back gobs of it every two weeks and it is choking my GPS, among other things - see pics - I also use a baster to blow it off my corals every few days. I use RO water to top off and change 25% of water every 2 weeks. You will see how the GPS is suffocating and where i have scraped the algae off the back glass. I add Iodide every week (on advice of LFS).
What could/should i be doing differently?

 

[spanko]

What are you dosing iodide for other than the LFS said to?
Does not look like coralline on the GSP to me. More like hair algae or byropsis.

 

[lazarus]

Yes - my point is i am ONLY getting algae growth on the corals and back glass - much more than i expected and after 5 yrs, i expected the back glass to look more like the LFS tanks, with a layer of coraline growth on it. Instead, it remains smooth but grows algae at an amazing pace.

 

[lazarus]

other ideas?

 

[spanko]

What kind of tank, fish only, reef? What kind of lighting and how old are the bulbs.
As you probably know algae needs nutrient in the water to grow. Could be an accumulation over time. Could be a maintenance of filters issue. Could be overfeeding. Could be coming in with your change or top off water. Could be all of the above. Probably gonna have to give folks more information on you system in total.

 

[lazarus]

Here goes:
Tank is 100g FOWLR - Corals include mushrooms, candy cane, chili coral, etc.
Bulbs are brand new - they are changed annually
RO water used to top off. Salt water comes from Scripps Oceanography Inst.
I dont have any mechanical filtration - I have a 20g refugium.
One possibility is an underperforming skimmer - i dont tend to get any accumulation in it until a few weeks out after a change.
I think theory about over-feeding and skimmer may make sense - but i am confident the water coming in is as pure as it gets.

 

[bang guy]

Coralline should be able to easily outgrow other types of algae on the glass as long as its needs are being met.
Waterflow + moderate light + adequate alkalinity - Phosphate = Coralline.
Find out which piece is broken.

 

[lazarus]

Well i just took a water sample to the LFS - who is generally regarded as the most honest in the business. He said nitrates are very low, but that if my tank and fuge are > 5yrs old then the sand needs to come out and be replaced, or better yet, go completely bottomless.
I was not quite prepared for this...but he did show me several tanks with plenty of coral, live rock and coralline on the back glass that have NO SUBSTRATE at all.
Has anybody gone this route? I have to admit that I like the idea of losing the substrate - if it makes maintenance easier and is inconsequential to the occupants.
Hope nobody minds but this is a big enough issue now that i will start another thread to be called - "Who is going bottomless?"

 

[number1gsxxr]

I don't think bottomless has anything to do with it. I have a 2+ inch at least sandbed and have more coralline than I can scrape. It seems like a have to scrape it once a week. I would read Bang Guy's post again and just check to see if any of those things are lacking.
It sounds like your bulbs are not an issue since they are new. How about checking your RO water? When was the last time you replaced the filters or tested the TDS? The fact that you are seeing nuisance algae makes me think you might have too many nutrients.