My Thoughts on GHA

Waters

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This post is based strictly on personal experience. I have dealt with GHA to some degree in pretty much every reef tank I have set up in the last 20 years. These have been set up with live rock, dry rock, and everything in between. I have come to a few realizations that seem to contradict what is commonly thought in the hobby.

It is normally posted that if you have GHA you have excessive nutrients (mainly phosphate and nitrate ), too much or incorrect lighting, and an inefficient CUC. I have come to realize that GHA actually needs very little nutrients and lighting to grow, and even flourish.

It is often said that if you have GHA, you have nutrients. If your test kits are showing 0 nutrients, then they are being consumed and held by the algae. I have had multiple tanks (both setup with live and dead, dry rock) that never showed elevated nutrients from day 1, until the day it was overrun with GHA. So what fed the algae? Phosphates always remained under .05 while nitrates always stayed around 5 from the time the tank was algae free until it was completely infested. Maybe the nutrients were bound in the rock and directly feeding the algae…but I guess that is a whole different issue. Result tells me that controlling nutrients in the water column will not guarantee an algae free tank.

Blackouts or reduced lighting are often suggested to combat algae issues. I always thought so too….until I tore down a mature reef tank to upgrade to something larger at which time I put all of my algae covered rock in a Brute container with nothing but my snails and shrimp. It remained this way for almost two months, doing regular water changes. The only light it received was when the 45W overhead basement lightbulb was flicked on maybe once or twice a day….otherwise the rock sat in the dark. The GHA actually flourished and grew in size with 0 light and low nutrients. Did it feed off itself........was it eating inverts lol??

Another solution to solving GHA issues is to add X number of snails to an already infested tank. The only algae free tanks I have kept (including my current setup) are ones where these snails (along with urchins, algae eating fish, etc.) are present from the very beginning. They will help maintain already shortly cropped algae, but they will not eat or clear mounds of long hair algae (with an exception being the sea hare). I had turbo snails the size of tennis balls in my brute with the live rock…..they didn’t touch the long hair algae strands.

So anybody that has had GHA free tanks which are over a year old, how did you do it? Is it bacterial? Is it filling it with frags early on to cover available rock? Growing coralline to take up space? Removing Co2 which could be feeding the algae (which in turn could also raise PH)? I honestly don’t know how to rid an infested tank of GHA without doing a RIP clean or using coral harming chemicals….which is the point of this thread. I need to hear some success stories lol. No, I do not have an algae issue now on my current 11 month old tank.......but I will at some point....at least that is what past history tells me.
 
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davidcalgary29

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Dose phyto. Add an urchin.

Top (I called it "the forests of Guilin" to cheer me up) is six months in; bottom is today. Not the prettiest tank, but it has broken lighting, so I'm giving it a pass.

4581384B-549D-4165-AD6F-922C64A0A668.jpeg 5E5830EF-99F8-4CD9-94A2-703387DB3826.jpeg
 
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Waters

Waters

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I have always had urchins who didn't do anything to established fields lol. Maybe phyto is the key......but isn't the point of phyto to mop up the same nutrients that GHA uses.....nutrients that aren't in a nutrient controlled tank anyways?
 

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I haven’t had much GHA in my 25 years or so of reefing (I know I’m doomed now!). It might be because I’ve always had a few tangs. Or maybe because I have used all or mostly liverock. Or something else plus some luck.

But I’m great at growing cyano, aiptasia, and vermatids!
 

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GHA really seems to be a biome issue rather than one dictated by nutrients. Mine disappeared in that tank when I increased a wide number of inverts into the system; the tuxedo urchin really went to town on it.

I started two tanks at work this year: one is a RSM250 with "rehomed" live rock; a juv yellow tang too care of the luxurious GHA growth pretty quickly. And yes, I've watched it eat it despite also having nori on a clip, so the fish do go after it. The other tank, an Evo, has tons of it. I harvest it out and feed it to the tang in the RSM250. It'll eventually disappear as the biome stabilizes, I think.

I dose about 20mL of phyto a week in the tank shown above -- usually in two 10mL doses. I put in just as much in my Evo, but I have filter feeders in that one.
 
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Waters

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GHA really seems to be a biome issue rather than one dictated by nutrients. Mine disappeared in that tank when I increased a wide number of inverts into the system; the tuxedo urchin really went to town on it.

I started two tanks at work this year: one is a RSM250 with "rehomed" live rock; a juv yellow tang too care of the luxurious GHA growth pretty quickly. And yes, I've watched it eat it despite also having nori on a clip, so the fish do go after it. The other tank, an Evo, has tons of it. I harvest it out and feed it to the tang in the RSM250. It'll eventually disappear as the biome stabilizes, I think.

I dose about 20mL of phyto a week in the tank shown above -- usually in two 10mL doses. I put in just as much in my Evo, but I have filter feeders in that one.
So are you dosing the phyto to use up nutrients and outcompete the GHA? Are you running elevated nitrates and phosphates in the tank that is loaded with algae?
 

Pico bam

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a tang heavy tank is usually gha free. When people say the don’t eat established gha I know what they mean but I could still drop a rock of it in my tang tank and they’d eat it just not an over abundance of the stuff. They’d go after bubble algae too believe it or not. Sometimes we eat food we don’t really like until we remember how bad it tastes.
 

Screwgunner

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Get some vibrant it will take 7 to 8 weeks and your hair will melt away. I keep my magnesium at 1500 and alot of flow. I do have a tang and fox face. I run a algea turf scrubber. So algea is under the tank not in it.
 

davidcalgary29

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So are you dosing the phyto to use up nutrients and outcompete the GHA? Are you running elevated nitrates and phosphates in the tank that is loaded with algae?
Yes, and no. I did start to dose phyto because of the GHA and a bad cyano problem. The skimmer really doesn't pull much skimmate any more (I haven't dumped it in months), even though I feed heavily (three times a day), so nutrient export is probably nitrogenous gas exchange. I do have some nuisance valonia, but it's not that bad.

NO3 in this tank is around 10, and PO4 was at .1 on my last test, which was about a month ago. I do little to the tank except RO/DI top-up three times a week; I even stopped regular water changes a few months ago, although I've got to step that up.

I don't think that phyto dosing is some wondrous cure-all, but it did seem to help with the GHA in combination with the introduction of the urchin. It didn't stop my cyano by itself; the addition of chemipure elite knocked that off.
 
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KonradTO

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The "nutrients are not low, it's just the GHA consuming it before you can measure" myth is the most twisted thing I have ever heard. I also had problems for months starting with my first reef tank, everything was covered with GHA. Nutrients were low until some kind users here suggested to keep them higher up and invest in a decent CUC. Some manual removal and a dino outbreak killed most of the GHA in the tank. GHA still grows very well in my fuge, and a tiny bit on my return nozzle, that's it, no more on rocks.
Hopefully now that I also got rid of dinos they won't come back. My strategy after reading Randy's article on silicate dosing, is to keep nuisance algae at bay by outcompeting them with diatoms via silicate dosing. So far it helped at controlling dinos, we'll see if it also keeps other stuff at bay.
 
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Get some vibrant it will take 7 to 8 weeks and your hair will melt away. I keep my magnesium at 1500 and alot of flow. I do have a tang and fox face. I run a algea turf scrubber. So algea is under the tank not in it.
I have had good luck in the past with Vibrant.....and I have also had it wipe out a couple of SPS tanks. I tossed it all in the trash lol. Not worth the risk to me anymore. I also have a lot of flow (two MP40s and two Wavs in a 105g) along with a couple of algae eating fish and a ton of snails, urchins, and cowries.....which is probably why I have had success so far with this build. I have thought about the scrubber but I need to research it more. Does it strictly remove nutrients (if so, that isn't going to help me) or does it somehow "persuade" the algae to grow there rather than the tank?
 

KonradTO

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Also my sensation is that a thing which gets underestimated is the role of a fuge and the balance between light intensity in fuge and DT. In theory if you make some nice cosy environment for nuisance algae to grow out of sight (fuge) then it will grow there first. If light is more intense in the fuge compared to the dt, algae will grow primarily there and compete with the ones in the DT.
Maybe I am wrong, but otherwise that's another reason why I might have less gha now
 

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GHA grows on reefs, stuff eats it.

I’ll add a quick vid of a scrubber screen submerged to allow access to pods;



Not to mention, tangs, rabbits, urchins and snails. There’s probably a bacterial slime element and shading also.
 
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Screwgunner

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That is the job of the scrubber . But instead of using blue light we go with a Red with a couple blue. To grow it faster. It removes toxins from corals nitrates phosphates . You have to adjust it to how much you feed . I feed 4 cubes and 2 pinches of flake . And a half sheet nori 2 times a week. I am using a 70 sq. Inch screen lite on bothsides on12 off 12 . My phosphates stay at .05 and my my nitrates 5 to 10 . I can almost see my birdsnest grow in front of my eyes. Went from 2 heads of zoanthids to 4 in under a month. I do not do water changes at all. More pods than I have ever had my flame angle is fat. From eating bugs. I dose alk. Cal. And trace. I do run my magnesium high at 1500.
 
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Waters

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That is the job of the scrubber . But instead of using blue light we go with a Red with a couple blue. To grow it faster. It removes toxins from corals nitrates phosphates . You have to adjust it to how much you feed . I feed 4 cubes and 2 pinches of flake . And a half sheet nori 2 times a week. I am using a 70 sq. Inch screen lite on bothsides on12 off 12 . My phosphates stay at .05 and my my nitrates 5 to 10 . I can almost see my birdsnest grow in front of my eyes. Went from 2 heads of zoanthids to 4 in under a month. I do not do water changes at all. More pods than I have ever had my flame angle is fat. From eating bugs. I dose alk. Cal. And trace. I do run my magnesium high at 1500.
Ok gotcha....unfortunately I don't need to reduce nutrients. My tank sits at those numbers now without a scrubber or running GFO. That was kind of the reasoning behind the original thread.....even with low nutrients, I have had tanks in the past get out of control with GHA. Sounds like it would be ideal for a higher nutrient system where water changes and skimming is not keeping up with nutrient export. The ability to grow and keep pods is definitely a good side effect of running one though.
 

typhune

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Wish I could figure out how to get rid of my GHA... I'm about ready to sell off and tear down the tank after having low / no phosphate / nitrate, trying blackouts, trying chaeto / scrubbers to out compete, tangs, etc. Just can't seem to win the battle.
 

KonradTO

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Wish I could figure out how to get rid of my GHA... I'm about ready to sell off and tear down the tank after having low / no phosphate / nitrate, trying blackouts, trying chaeto / scrubbers to out compete, tangs, etc. Just can't seem to win the battle.
Don't give up. I was in the same place few months ago. No GHA in sight now :)
 

KonradTO

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Wish I could figure out how to get rid of my GHA... I'm about ready to sell off and tear down the tank after having low / no phosphate / nitrate, trying blackouts, trying chaeto / scrubbers to out compete, tangs, etc. Just can't seem to win the battle.
Also do not keep low nutrients, its pointless. Remove manually and once other stuff grows on the rocks it will stop growing
 

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