Dry rock and phosphate leech?

[Channas]

Hello reefers
So my headscratch in his evening is:

Do you guys experience high phosphates when using dry rock? Compared to live rock? The first tank i ever started was with live rock only, i had stable phosphates after 2 months at 0.06ppm it was stable there somewhat for 4 years using the same husbandry i use on my mixed reef 740L tank today which is 10-15% wc weekly, refugium and a oversized skimmer. Sure i understand the bioload and how much i feed come into consideration as Well but that tank was 200L with sump and was fed 2 frozen cubes a day and my 740L gets fed 3-4 frozen cubes a day.

These other 2 tanks i started up with dry rock, skyrocketed in phosphates, the seahorse tank (280L total volume cube) with 80-90% dry rock and 10-20% live rock has 0.4 phos as we speak i do know seahorses make a mess and i do 30% wc every week and use gfo inside the sump but it has very little effect to no effect of the phosphates because the phosphates are back up the next day or 2.

My other tank (740L total volume) with 50/50 dry/live rock is at 0.15 ppm as im writing this but for about 6 months it was locked at 0.25 ppm phos, is it possible that dry rock leech alot of phosphates for a period of time when first introduced, compared to live rock? It sure seems like it.

Any inputs about this would be great

 

[Randy Holmes-Farley]

Rock (live or dead) will have phosphate on it that reflects the last level of phosphate it was exposed to. For dead rock that is mined, that can reflect ground water running through it.

 

[Channas]

Rock (live or dead) will have phosphate on it that reflects the last level of phosphate it was exposed to. For dead rock that is mined, that can reflect ground water running through it.

Yeah i understand that but are dry rock more prone to phosphate leaking? I belive i am experiencing it in the seahorse tank since i did start that tank with 100% dry rock and sand for about 2 weeks before adding the live rock (lfs didnt have any at the time)

 

[Randy Holmes-Farley]

Yeah i understand that but are dry rock more prone to phosphate leaking? I belive i am experiencing it in the seahorse tank since i did start that tank with 100% dry rock and sand for about 2 weeks before adding the live rock (lfs didnt have any at the time)

No, if the dry rock (or live rock) was loaded with phosphate to a level higher than equilibrium with tank water, it will release.


, if the dry rock (or live rock) was loaded with phosphate to a level lower than equilibrium with tank water, it will bind phosphate.

It’s not a dead vs live difference. It’s what’s on the surface of the rock that matters, and it can go either way.

 

[Channas]

I see thank you

 

[Finn450]

Had a system years ago that phosphates were always high...lead to GHA. Did everything. Nothing seemed to bring them down. A friend said it may be the rocks...it was.

 

[Channas]

Had a system years ago that phosphates were always high...lead to GHA. Did everything. Nothing seemed to bring them down. A friend said it may be the rocks...it was.

Yeah im dealing with gha in the particular tank that has the most dead rock during start up and it’s the worst outbreak i have ever experienced. I suspect it’s the rocks too. I run gfo in it now but doesnt seem to do anything

 

[Randy Holmes-Farley]

Bad phosphate scenarios may require lanthanum to be cost effective. The rocks can hold massive amounts.

 

[Channas]

Bad phosphate scenarios may require lanthanum to be cost effective. The rocks can hold massive amounts.

Yeah i dont want to use that stuff, its a seahorse tank and im not going to risk it, i will keep up my 30% wc and increase the gfo amount until i see the phosphate change for the better. I do add tetramensis phyto to the tank and the day after a phyto dose i see a small drop in phosphates for a day then its back up.

 

[exnisstech]

Had a system years ago that phosphates were always high...lead to GHA. Did everything. Nothing seemed to bring them down. A friend said it may be the rocks...it was.

I don't know if dry rock releases more PO4 than live rock but I don't think high PO4 is the cause of GHA. I have a tank that has never been below 0.4 and often will be in excess of 0.9 which is as high as my tester reads and I have O nuisance algae. I have another tank that runs PO4 0-0.02 and GHA loves it.

 

[Channas]

I don't know if dry rock releases more PO4 than live rock but I don't think high PO4 is the cause of GHA. I have a tank that has never been below 0.4 and often will be in excess of 0.9 which is as high as my tester reads and I have O nuisance algae. I have another tank that runs PO4 0-0.02 and GHA loves it.

Yeah in my mixed reef after a month or two battle with gha and won over it the phosphates creeped up to 0.25 and was locked there for about 6 months and at times im sure it was higher as Well but with 0 gha and still 0 gha in the display but it does grow a small Patch inside the refugium.

 

[Channas]

However i do belive that if there is a balance between nitrate and phosphate there is less issues with gha, my seahorse tank sits after todays testing at 0.38 ppm phos but nitrate at 9.7ppm so it’s a clear imbalance between the two nutrients

 

[exnisstech]

Ya mine that runs high has been up for 2+ years has always been high. I'll add a little rowaphos when I see a flashing 0.9 just so I can get an actual number. Not sure why but having an actual test result makes me feel better.
An imbalance is interesting. My NO3 is also high at 30-50. My problem tank that runs at or near O PO4 also runs NO3 near zero. My GHA is slowly receding after a year but my rocks and sand are algae free but the acrylic back wall is covered along with anything else plastic in the tank. Its all too much for my simple brain to understand but it seems like some surfaces are being populated with beneficial bacteria or something similar and out competes GHA but the good stuff seems to struggle to populate the plastic first.

 

[Channas]

Yeah this hobby is crazy and yes plastic could be harder for the ”good” bacteria to colonize however with that amount of gha i would suspect that the cause of your ultra low system is because of that gha on the backwall, now is the time though to remove it all by hand and possibly be gha free, and good time to try my theory about nutrient balance, it is something that i have observed when i do reach a somewhat good balance between nitrate and phosphate the gha becomes really easy to fight and stays away as long as the balance is maintained.

 

[commod0re]

So I’ve only used dry rock so I have no real experience with live rock to compare to, but, I’d say that so far I’ve struggled with chronically low phosphate levels rather than the opposite