My phosphates are creeping up

[ozorowsky]

Hi all,

I have a 340 gallon reef tank with alarge sump probably 150 gallons. I don't do water changes often but when i do i open a valve teed off my return that drains water out to my sink drain. Then i have a water line that runs through my ro di to a float valve and the float valve keeps my water level consistent.

For salt, i have a filter sock suspended in my sump i add salt there let it dissolve. People say not to do this but i don't understand the harm. Corals look healthy albeit not growing as fast as id like. Only issue is my phosphates are at 2.0 currently.

Back to my sump. My return area has alittle life rock and chaeto. Then it flows to an area housing my euro reef protein skimmer and my skimz bio pellet reactor. After that it flows to a final area where my return pump is as well as a smaller pump which pumps water through a uv sterilize and dumps it back by the protein skimmer.

I'm about to add two little fishies kalk reactor with small pump that will turn on for 5minutes a day with very little kalkwasser.

I just added some gfo, but any tips on how to bring phosphates down? Tank has been up about 7months now.

Any other thoughts how I'm running things? Ph reads 7.5 to 8.0, salinity 1.026 dkh 10 ca 430 0 ammonia/ nitrite/ nitrate all per api test kits.

[bertoni]

If you think the phosphate level might be affecting the coral growth, I'd guess that lanthanum chloride dosing is the most practical way to reduce the level. That requires a filter sock to catch the precipitate that forms, which takes some effort to manage. Other than that, it's going to take a lot of GFO.

[RobZilla04]

What test kit did you use to test the phosphates?

Typically the suggestion when you get an erratic test result is one of two things: 1 - retest with the same kit making sure everything is clean to start with and carefully follow the procedure and 2 - test again with another brand test kit to confirm the result.

Next I would question what negative effects from the increasing phosphates are you observing. Other than corals not growing as fast as you'd like (they grow slow in general) are you seeing an increase in algae?

My suggestion would be to keep an eye on things for a little while and monitor the levels weekly or twice a week. GFO can irritate the corals and strip phosphates quickly leading to additional problems.

[ozorowsky]

Yes there is alot of algae on the acrylic. I have to wipe it daily. Some of it is pretty called on i have to use the magic eraser to remove.

I have about 6 tangs and 25 or so total fish in there. I feed nori once aday. Frozen mix once a day. Pellets once a day and flakes once a day.

My Duncan's pop new heads every week. My torches and hammers not doing much.

I have a deresa clam doing just fine for what it's worth.

Right now I'm doing about 15 gallon water change daily to try being phosphates down. I'm waiting on small pump to get here to let the kalkwasser reactor start putting alittle kalkwasser in the tank. I hear that helps get things in check?

[RobZilla04]

15g water changes on a system with total volume of 490ish gallons = about 3% Water changes of that size will have relatively zero effect on reducing phosphates.

Looking at your feeding regiment I would suggest cutting back for starters.

I'd also suggest a Hanna, Red Sea, or Salifert Po4 test kit to get an accurate reading.

The dusty algae on the glass is nearly an issue for 100% of reefers. That is not indicative of an "algae problem" per se, yet as you mention it could be a signal that you are having to clear it daily.

[tmz]

Kalk will have little if any effect on PO4;any continous associated pH increase might. I'd try cleaning up any detritus accumulations with some gfo for an initial reduction .lantanum chloride will work but requires extrem care inlcuding slow dosing and adeqate small micron filtration to prevent free lanthanum and precipitant from entering the tank.

[ozorowsky]

Kalk will have little if any effect on PO4. I'd try cleaning up any detritus accumulations with some gfo for an initial reduction .lantanum chloride will work but requires extrem care inlcuding slow dosing and adeqate small micron filtration to prevent free lanthanum and precipitant from entering the tank.

Do phosphates in any way act like nitrites where they get absorbed by nitrates? Meaning will phosphate counts just grow and grow or is there some trick to get phosphate to die off? Or does it have to be water changed out/subsided?

[RobZilla04]

Do phosphates in any way act like nitrites where they get absorbed by nitrates? Meaning will phosphate counts just grow and grow or is there some trick to get phosphate to die off? Or does it have to be water changed out/subsided?

It gets consumed by living organisms (coral, macro algae, bacteria, etc). Taking 50% water out and replacing with water that has say 0.000 Po4 will cut phosphates in half, but as you feed and organisms create waste they increase again. Trick is to balance input with removal/consumption. Generally this takes time.

[ozorowsky]

So is 2.0 per API test kit going to kill my corals? How do I get it under control? I have read the increase in ph by dosing kalk helps significantly. I also heard bio pellets help some. I have been doing a 20 gallon water change or so every morning, and am about to cut feeding back to 1x a day frozen food, and 1x a day flakes/pellets. Along with 1x a day nori.

I'm just trying to get this under control before it becomes a real problem and crashes my tank. Or maybe I'm worrying too much?

[Tripod1404]

Get a better test kit before doing anything drastic. Best option is a hanna phosphorus ulr checker. 2ppm, if correct will give you massive amounts of algae that can take over a tank in few weeks and cover everything. And yes, it can kill corals.

[bertoni]

I agree that getting a second opinion on the test kit would be worthwhile before doing anything drastic or costly.

Predicting exactly what 2.0 ppm of phosphate will do is impossible. Some people report no problems with a level like that, and others seem to have troubles.

I agree that the feeding level might be the source of the phosphate. Water changes will work, but they might be very costly, given the phosphate level. I'd consider more like 20% changes at a shot, and the live rock might leach phosphate back into the water at a rapid rate, so it could take a very long time to remove the phosphate that way.

[tmz]

Do phosphates in any way act like nitrites where they get absorbed by nitrates? Meaning will phosphate counts just grow and grow or is there some trick to get phosphate to die off? Or does it have to be water changed out/subsided?

This article provides a lot of good information on phosphate in aquaria:

http://reefkeeping.com/issues/2006-09/rhf/index.php

Phosphate does not act like nitrites , though phosphate species can shed H at higher pH.

Inorganic phosphate( aka orthophospate/ Pi )includes :

H2PO4<--->HPO4<--->PO4.


The proportions of each species depend on the pH; more H2PO4 at lower pH and more PO4 at higher pH. The H makes binding to carbonate surfaces less strong ; so shifts to more H2PO4 may free up more PO4 into the water or limit binding ( sinking)

[Dan_P]

Do phosphates in any way act like nitrites where they get absorbed by nitrates? Meaning will phosphate counts just grow and grow or is there some trick to get phosphate to die off? Or does it have to be water changed out/subsided?

Just to clear up some chemistry jargon...nitrite is be oxidized by bacteria to nitrate. Phosphate is a stable chemical species that will last forever in an aquarium unless it reacts to form an insoluble precipitate, e.g., lanthanum phosphate, is adsorbed onto something, e.g., GFO or aragonite, or removed with a water change. Algae and other organsms can assimilate phosphate, but unless these are removed, the phosphate is not removed from the system.

[ozorowsky]

Just to clear up some chemistry jargon...nitrite is be oxidized by bacteria to nitrate. Phosphate is a stable chemical species that will last forever in an aquarium unless it reacts to form an insoluble precipitate, e.g., lanthanum phosphate, is adsorbed onto something, e.g., GFO or aragonite, or removed with a water change. Algae and other organsms can assimilate phosphate, but unless these are removed, the phosphate is not removed from the system.


Thank you. 20 gallon water change a day should lower the phosphates and get them in check right? What do people do normally to keep phosphates in check?

[bertoni]

There are a lot of factors involved in choosing a method of reducing phosphate. First, there's the input rate vs the export rate. Reducing the input rate amounts to reducing feeding, which might or might not be appropriate. If the input rate is not changed, then you'll need to increase the export rate if you want to reduce the level.

Some of the more popular ways to export more:
&nbsp;&nbsp;&nbsp; 1) better skimming
&nbsp;&nbsp;&nbsp; 2) GFO
&nbsp;&nbsp;&nbsp; 3) carbon dosing
&nbsp;&nbsp;&nbsp; 4) lanthanum chloride
&nbsp;&nbsp;&nbsp; 5) growing and harvesting a macro algae

Water changes will work if the problem is due to a one-time phosphate spike. For example, if a bunch of food gets dumped into the tank by accident, water changes can help a lot. Water changes can help when the input rate is close enough to the export rate that you can afford the time and money to do the changes.

A 20g change on a system with maybe 200-300 gallons of water will reduce the phosphate level about 7-10%, but if the feeding rate is adding phosphate quickly enough, the level will bounce back up to the previous level fairly quickly. In addition, live rock will adsorb phosphate and release it when the phosphate level in the water drops enough.

For very high levels, lanthanum chloride probably is the most cost-effective approach, although it requires dosing into a water that then is filtered to remove the precipitated lanthanum phosphate.