Found PO4 source, question on live rock

After doing everything possible to bring it down (believing it just spiked after a tank move), finally investigated last night. I set up a tuppaware container with fresh saltwater, then rinsed and placed a piece of live rock in. Tested right then at 0 PO4. Two hours later, that water was testing at >1.0 PO4!

I understand I have a couple of options. 1) continue doing what I'm doing, at great expense of PO4 removal aids and effort in GHA removal, and could takes months/years, 2) cook the rock, which could take weeks or months, and might be somewhat difficult given I already have livestock, or 3) replace rock.

I'm leaning at replacing the LR, and from what I'm reading, would it be best to just buy dry base rock and place that in my tank while leaving a few pieces of my current LR in place to "seed" the base rock? It's cheapest, and I dont think I run the risk of a cycle (I believe???)?

Any input is appreciated. My boss and I are getting frustrated with the amount of cyano we're dealing with, and the tank is quickly losing it's appeal to her.

 

IMO yes and won't risk cycle (just be careful removing the "dirty" rock)

 

For a 90 gal tank, how much LR should I leave in the tank as "seed"? Current bioload: 1 clown, 1 firefish, 3 chromis, 1 blue hippo, 1 yellow tang.

Any suggestions on where I can find quality dry rock on a budget? I was looking at reefcleaners.org... they always have good stuff.

 

In many instances where P04 is in the rocks...it may take a long time to get rid of. The rock will absorb p04 and release it and the cycle starts over. I had an issue very similar with a HA problem from LR that was bought from another local reefer. I did the same test by putting it in a bucket and testing the freshwater. After leaving the rock in there for a while and doing about 15 water changes on it. The P04 finally came down but not by much. Best to just replace the rock all together and avoid future headache. Another, good option is to run GFO in a reactor to help battle any remnance. it wont rid the tank of P04 but it will keep it under control.

 

baserock gets seeded pretty quickly in an established tank. I think that would be fine. I recently added some baserock to a well established 29g and it was pretty coralline covered within about one to two months. Adding to a less established tank seems to take significantly longer though, but should at least get populated with bacteria quickly.

GFO can often help to though. As the po4 leaches out, it is absorbed by the GFO. This probably is fine 90% of the time, unless it is really heavily contaminated. The only issue with this, is you will need to use a lot of GFO, which will drop your alkalinity quickly. So, you will need to monitor alk closely and dose as needed.

 

Also, just to add... if you go the GFO route, make sure to gradually increase the amount of GFO. If you add too much, you may stress your corals. LPS corals especially seem to be sensitive to sudden drops in po4.

 

not very much at all to reseed... in fact, you could probably leave none in and let the substrate do the reseeding...

 

Agreed.

Do the scrape trick on all the rocks as you pull them out. Just scrape a lot of the pretty algea off the rock in front of a power head and viola consider it seeded.

 

Thanks. I'm thinking with the amount I'm seeing leach from the rock, and the amount of rock I have, it'd be cheaper, and cleaner, to go with new rock. I dont have any LPS/SPS corals yet, I've been waiting on this darn PO4 problem before I place any corals in the tank.

Trying to be patient.

 

are you using rodi water reading 0 tds??? if it were my tank i would just run gfo, before i spent 300$+ dollars on more dry rock..but thats me...i would be unsure i wouldnt have the same problems,,

a fuge and running gfo will take care of your nitrates and phosphates and doing water changes with 100% 0 TDS water will take care of it...unless you dont like the look of your rock, then i wouldnt replace live rock for a 90 gallon tank..thats like 400$