Odd test results

[tampasnooker]

I am getting some out of this world chem readings on a 300 gal reef that I care for. Large water changes, heavy skimming do not affect it. My assumption is that something is causing interference on my chemical tests. Calcium and Phosphate are testing unbelievably high but the corals and nems are just fine.

Just to eliminate a couple obvious concerns - the test kits are used on 30+ tanks a week. User error and faulty test kits are not likely, given the consistency that they give us everywhere else, including 2 other tanks in this office.

The only variable I can see between this and all the other tanks in our care (since we took over in November) is that store bought shrimp are used to feed the larger fish and wolf eel in this tank and it contains Sodium Tripolyphosphate and Sodium Bisulfite as preservatives. We ceased use of these shrimp 2 weeks ago upon this discovery - apparantly these preservatives are used in many grocery store bought shrimp. Also, the previous service allowed indescriminate use of A+B additives.

I don't think that these figures are physically possible, but I'm stumped as to what's causing them. Z's and P's, Frogspawn, candycane, Riccordea, RBTA, leathers, star polyp etc are all doing great. Heavy use of GFO can't bring the level down to a measurable level (hanna photometer) and Ca varies from 600's to 800 without any additives. ROX carbon does not affect test results. We did large water changes for the first two months but reduced to 10 gal EOW since there was no change in chemistry. A beast of a Euro Reef pulls out the same goo as normally performing aquariums - no indication from the skimmate as to elevated nutrients.

Here's a rough summary of chem - EOW readings. No supplements are being used besides occasional alk buffer.

Sal KH Ca PO4
1.025 8-9 820 >2.5 ppm - never tested below this.
1.025 9 880 "
1.025 8-9 760
1.025 10 680
1.024 7-8 760 Reduce w/c from 50 gal to 10 gal EOW
1.024 9 640 IO, RC salts used
1.024 8 640
1.025 8 700
1.024 9 660
1.026 9 640
1.025 8 700 >2.5 still...

Kits used:
Ca Aquarium Pharm
KH Aquarium Pharm
PO4 - Hanna photometer
Cross reference Ca occasionally with Salifert - similar results.

Any thoughts on what is throwing off the chem analysis would be appreciated.

 

[ritter6788]

600+ calcium isn't harmful as say 15+ dkh alkalinity. It's very possible for corals to survive in these conditions. I've also heard of tank with 2.+ phosphates. Doesn't mean it will kill lps or softies but they likely won't grow much if any. Heavy use of additives and heavy overfeeding in a 300 gallon will take a lot of export and water changes to correct.

 

[wysiwyg]

what does it have for a substrate. there is some debate about aragonite releasing calcium into the water as it breaks down

 

[tampasnooker]

I'm not convinced that the results are correct. 7 months of PO4 over 2.5 ppm should have melted any coral with a skeleton months ago. If 3 months of 50 gal w/c's didn't change the chem and there is no additional calcium added to the system, I should have seen Ca and PO4 drop. Neither has budged. More puzzling is the Ca rising again without any addition. 10 gal of IO in a 300 gal tank every other week is not a significant source of any element. The aragonite should not be dissolving at this rate - or else we'd all be using it to buffer tanks.

 

[Steelerfan747]

I dont know if you mentioned this but are you dosing calcium? If so maybe theres a problem there.

 

[tampasnooker]

Nope. The only chemical changes are via 10 gal water change (in a 300 gal tank) EOW.

 

[robert]

This is a weird one as you obviously know what your doing with testing...

So the challenge is to explain where the excess calcium and phosphate are coming from. You've done considerable export which should have brought levels down but haven't - therefore the source is in the system and the source is robust.

A reverse of a potential precipitation reaction which is possible at the pH ranges of a reef tank and especially the sand bed:

2Ca[2+] HPO4[2-] + 2OH[-] -> Ca2HPO4(OH2)
3Ca2HPO4(OH2) -> Ca5(PO4)3(OH) + Ca[2+] + 2OH[-] + 3H20 (hydroxylapitate)

Pure SWAG...

If you were running a calcium reactor I would have suspected bone - specifically the hydroxylapatite in the bone - but I suppose bacterial decomposition of bone somewhere else in the system is a possibility? Perhaps in a RDSB or maybe not all of the rock work is coral.

 

[robert]

How long has the tank been running?

 

[robert]

The shells of some crustaceans contain hydroxylapitate. We're the shrimp shelled? I'm totally guessing...lol

 

[chris13115]

calcium a little high, add some alkalinity to drop it and raise ph by a few

 

[ritter6788]

I'm not convinced that the results are correct. 7 months of PO4 over 2.5 ppm should have melted any coral with a skeleton months ago. If 3 months of 50 gal w/c's didn't change the chem and there is no additional calcium added to the system, I should have seen Ca and PO4 drop. Neither has budged. More puzzling is the Ca rising again without any addition. 10 gal of IO in a 300 gal tank every other week is not a significant source of any element. The aragonite should not be dissolving at this rate - or else we'd all be using it to buffer tanks.

Since this isn't your tank then maybe someone is adding to the system and not telling you. You mentioned in your first post the indescriminate use of A+B additives. Maybe someone is still feeding and adding to the system that you don't know about. I can't imagine any other explanation of rising calcium if none is being added to the system.

 

[beaslbob]

try another calcium kit or get a second opinion.

if true then cut back on two part and let the calcium come down in its own.

my .02

 

[tampasnooker]

The shells of some crustaceans contain hydroxylapitate. We're the shrimp shelled? I'm totally guessing...lol

The owner is lazy about removing the shells. I'll correct that. The tank is several years old.

 

[tampasnooker]

Since this isn't your tank then maybe someone is adding to the system and not telling you. You mentioned in your first post the indescriminate use of A+B additives. Maybe someone is still feeding and adding to the system that you don't know about. I can't imagine any other explanation of rising calcium if none is being added to the system.

I've made sure no additives are used. All they do in the office is feed and top off the tanks. Occasionally I add Sodium Carbonate/Bicarbonate mix to see if that will help drop Ca. There are no real consistent results from doing this.

 

[tampasnooker]

Just returned from visiting this aquarium. PO4 still reading over 2.5; Ca tested at 660 (down from 800 two weeks ago) and pH was just 7.8. I'm not sure if that is from heavy feeding or the lids on the tank so I removed the lids to see if off gassing CO2 helped any.

 

[robert]

The owner is lazy about removing the shells. I'll correct that. The tank is several years old.

I wasn't suggesting that shrimp shells are the cause...Some shell - lobster for instance have high phosphate content similar to bone - but I don't think shrimp shells fall into that group.

In waste-water treatment - a general process called EBPR (enhanced biological phosphate removal) - uses bacteria to form complexes out of calcium and phosphate. The sludge produced holds a surprisingly high phosphate content (10% or more) and depending on pH and environment, is reversible. EBPR can take place in fully aerobic conditions or in a mix of aerobic/anaerobic conditions - I run the aerobic/anaerobic EBPR system external to my tank for phosphate removal, but I can see no reason why the fully aerobic process could not persist in a reef system and over time deposit a considerable quantity of highly phosphate enriched sludge in the sand bed.

Of course it could also be as you suspect, that the test results are in error.

I would suggest en experiment that might help determine if the phosphate tests are reflecting reality-

Test a sample of tank water for phosphate.
Next treat the water with lanthanum chloride and test again.
Finally take some freshly mixed water and treat it with lanthanum chloride the same way you did the tank water and test this as well.

If you seen no difference in readings between the lanthanum treated tank water and the non-lanthium treated tank water - I'd say the test cannot be relied on and some other agent is causing a false positive.
I would expect the lanthanum treated tank water to read the same as the freshly mixed water treated with lanthanum chloride. - I'd be curious to know if its not.

Something to try anyway.

Robert.

 

[robert]

Just to be clear - treat a sample of tank water with the lanthanum chloride - not the tank.

If the lanthanum chloride drops the test result - I suspect your really seeing phosphate.

 

[lpslover]

Very weird case indeed.

over time deposit a considerable quantity of highly phosphate enriched sludge in the sand bed.

I have seen older tanks that are otherwise in perfect shape end up with an unabating high PO4 levels (though never quite that high). Only permanent solution I've found, unfortunately, is to transfer all the corals to buckets for holding while the rock is removed and scrubbed, and the substrate is siphoned absolutely spotless before restacking the rock and corals. This results in a huge water change, which helps dilute down the PO4, then the tank gets a lanthanum dose to help lock up any residual in the rock and substrate. The corals will stress, but should recover. The fish will be deliriously happy. Give it a week or two to restabilize, then deep clean and replace all the filtration media and components.

Also related: I have noticed that calcium consumption slows down in my tanks when either A) The GFO needs replacement. B) Strontium is low. So maybe if you can bring the PO4 levels under control the calcium consumption will rise and the level will begin to drop. Also Salifert does make a good Strontium test kit (the SeaChem one is a nightmare) and it may be worth checking the Strontium level. Since I started testing for and dosing Strontium in my tanks the Mushrooms in my softy tank went absolutely nuts and started splitting almost daily, and the calcium consumption in my stony tank picked up about 30% a week.

Good luck. Let us know what happens!

 

[tampasnooker]

I just picked up some Lanthanum Chloride to clean up some FL coral rock before culturing it. I have heard of people using it in established tanks but do not know a dosage that is safe for livestock. Any suggestions for a starting dose? I understand you want to run all water through a good mechanical filter to remove the Lanthium Phosphate that forms and precipitates.

LPS - I'm a mushroom nut and collect unusual rhodactis mostly. I'll dust off the old Strontium kit and see if that works the same for me.

 

[lpslover]

I've personally used the CarribSea liquid PO4 remover as per the directions which I am assuming is lanthanum based. That calls for 5mL per 10 gallons to remove up to 1ppm PO4.

I have also heard of people using SeaKlear to good effect, though I haven't done so personally. Joe Y. uses it on his 20,000 gallon tank. His dose works out to .00375mL/L. He dilutes 300mL in 5.25 gallons of RO water and drip feeds it to the sump. Article at

http://www.coralmagazine-us.com/content/foiling-phosphate

talks about this method.

Do let me know how your mushrooms do as well. I'd be interested to hear if you get the same results.