New Swiss 1900 liter (500G) Build

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Laith

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You lose some PO4 - if it is biological uptake or if you are filling the chemical reserves (sand, rocks and so on) - I can´t say. But I have seen this before. Near zero - adding - still near zero - adding - still near zero - after sometimes - there is the ketchup effect - suddenly readings. You have to measure rather much until you hit the saturation point (if there is any). You must also count with the accuracy of the tester - its about 0.02 ppm (or around 5 ppb) - If you read 2 ppb - it can be from 0 to 7 ppb. If you read 0 ppb - it could be up to 5 ppb. If you read 5 ppb - it could be between 0 and 10 ppb. It is not easy in these low values :D

Sincerely Lasse
Yes, I see exactly what you mean about a potential "ketchup" effect where the numbers suddenly jump. I will keep an eye on that daily!

Thanks for the input! ;Happy
 
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Ok, after 12 hourly doses of .003ppm of PO4 this morning's test shows 1ppb (.003ppm) of PO4 in the tank. With the margin of error of the Hanna test it might as well be 0.

I have been advised that perhaps trisodium phosphate is not the best compound to use as it disassociates into Na and PO4 much more difficultly than for example KH2PO4 (monopotassium phosphate). Therefore you are not actually adding much biologically available PO4.

Can someone confirm or not (@Randy Holmes-Farley or @Lasse perhaps)?

Then I can get some KH2PO4 or even see if my LFS has any Seachem Flourish Phosphorous in stock.

In the meantime I'm going to double the dosing of the trisodium phosphate and see what that does.
 

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I do not know - I have only used KH2PO4. However - I do not think that just the lower total solubility for trisodium phosphate is a problem because we use very weak solutions. The salt needs to be hydrolysed into pure orthophosphate (PO4) and if that process is faster according to KH2PO4 I can´t answer. Normally KH2PO4 is used as a fertilizer for plants - but I think the main reason for that is that you also add K (also a macronutrient for plants) - In seawater - you normally have enough of K. @Randy Holmes-Farley - correct me if I´m wrong.

Sincerely Lasse
 
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I do not know - I have only used KH2PO4. However - I do not think that just the lower total solubility for trisodium phosphate is a problem because we use very weak solutions. The salt needs to be hydrolysed into pure orthophosphate (PO4) and if that process is faster according to KH2PO4 I can´t answer. Normally KH2PO4 is used as a fertilizer for plants - but I think the main reason for that is that you also add K (also a macronutrient for plants) - In seawater - you normally have enough of K. @Randy Holmes-Farley - correct me if I´m wrong.

Sincerely Lasse
I've ordered KH2PO4, should be here next week. Curious to see if at the same dosages the PO4 measures differently!
 

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I was trying to say that I will also be using KH2PO4, since I already have it and use it in freshwater for my planted tanks. I can also send some info, but since I only have drop tests I can´t test it as regularly as you. But I will be checking that info, since my phosphates are also very low if not 0 at all.
#Lasse what is your experience with KH2PO4???
 

Lasse

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I was trying to say that I will also be using KH2PO4, since I already have it and use it in freshwater for my planted tanks. I can also send some info, but since I only have drop tests I can´t test it as regularly as you. But I will be checking that info, since my phosphates are also very low if not 0 at all.
#Lasse what is your experience with KH2PO4???
It works well for me. - 4.3 g to 1 liter RO water. 1 ml of this stock solution raise 100 l with 0.03 ppm

Sincerely Lasse
 

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It works well for me. - 4.3 g to 1 liter RO water. 1 ml of this stock solution raise 100 l with 0.03 ppm

Sincerely Lasse
Awesome... My calculations I had to use 2g in 1 liter of RO water to raise 0.02ppm in my 90 liter tank. Since yours works I will be using it.
Thank you very much, friend #Lasse
 
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I have received my order of KH2PO4... but I have a question that someone may be able to answer:

Is the PO4 in Na3PO4 still measurable by a PO4 test such as the Hanna ULR yet still may not be biologically available to the organisms that need it? In other words, even if the the test kit is showing that PO4 is present, the PO4 is still bound to the Na3 and therefore less available?

Or does the test only show PO4 when it is already disassociated from the rest of its compound?
 
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Lasse

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Both KH2PO4 and Na3PO4 will go in solution directly in this low concentrations we use. Both will form free PO4 (orthophosphate) instantly. All PO4 in both formula will be dissolved directly. It will be direct available for photosynthetic growth. All type of our hobby tests (incl all Hanna) will analyse free PO4

Sincerely Lasse
 
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Both KH2PO4 and Na3PO4 will go in solution directly in this low concentrations we use. Both will form free PO4 (orthophosphate) instantly. All PO4 in both formula will be dissolved directly. It will be direct available for photosynthetic growth. All type of our hobby tests (incl all Hanna) will analyse free PO4

Sincerely Lasse
Thanks for the excellent clarification Lasse! ;Happy

After having raised my Na3PO4 dosing to 0.8ml of my solution 24x a day, or the equivalent of 0.192ppm of PO4 a day, for several days now I've been measuring between 0.021ppm PO4 and 0.046ppm PO4 in the tank with daily testing. That means that the tank is using up between 0.146 and 0.171 ppm of PO4 per day (of course ignoring the Hanna range of error).

Not sure whether this is a high level of uptake (?) but if so I guess it can be due to:

- Relatively PO4 starved organisms "catching" up on their PO4 deficiency by sucking it all up;

and/or:

- My ceramic dry rock and gravel binding up a lot of the PO4.

Now that I've stayed away from having 0 PO4 in the tank for about five days I've noticed that the coral colors look slightly deeper... and the small amount of cyano that had appeared seems to be dying back.

Given Lasse's feedback above I'll keep using the Na3PO4 solution (no need to throw away the liter of it I mixed up!) and keep the daily dosing as it is and follow the progress...
 
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Here are two interesting articles I found when researching PO4 uptake rates. I haven't read them thoroughly yet as have not had the time but...


 
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On another subject, the salinity in my tank has been creeping upwards steadily. ATO is working fine (in fact I've installed two redundant Tunze Osmolator systems, one as a backup of the other) so the only thing that I could think of was that the AWC was putting in more fresh saltwater than it was taking out.

I remembered that when I first calibrated the Litermeter III that I'm using for my AWC, I calibrated both pumps (the one emptying water and the one refilling) at the pump heads instead of the actual working distances. The pump taking out water is pumping water out of the tank to the kitchen sink drain which is about five meters away. The pump pumping water from the fresh SW tank to the sump is pumping the water only about 50cm away.

You can see where this is going no? ;Shamefullyembarrased ;Shamefullyembarrased

My original calibration told the Litermeter that the fresh SW pump was pumping 176ml/min and the pump taking water to the drain was pumping 136ml/min.

Well, today I re-calibrated using the actual tubing and distances: fresh SW pump: 150ml/min, drain pump: 39ml/min!!

So when I had set both pumps to pump 16.5 liters of water per day (16.5liters out and 16.5 liters in), a lot more water was being pumped into the sump than was being taken out.

Lesson learned: don't take shortcuts! ;Happy
 
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To follow up on my low PO4 issue, I raised the dosing amount to the equivalent of 0.192ppm per day spread out over 24 hourly doses and tested PO4 using the Hanna ULR twice a day (07.00 and 19.00). After about a week at this dosing volume my PO4 levels reached 0.071ppm... 12 hours later they were at 0.083ppm so I calculated that if I wanted to stay around 0.07ppm then I was overdosing 0.012ppm. I lowered the dosing to the equivalent of 0.168ppm per day and now the tank has stabilized at between 0.07ppm and 0.08ppm.

Nitrates steady at 6-8ppm.

The colours of the corals have definitely improved: they are deeper and no longer so pale. Not much difference in polyp extension but I've always had some doubt how much polyp extension really shows and in any case my polyp extension has always been pretty good. Too soon to say anything about growth rate.

Cyano is still there but receding day by day... ;Joyful
:D


I should be receiving my order of the Fauna Marin Amin amino acid additive soon. I'm curious to see the impact this will have though I will start with very low doses as I don't want to suddenly find myself battling too high nutrient levels.

I have never been a number chaser but in this instance in my opinion it was necessary. ;Happy
 
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Quick update:

- I took apart and cleaned the Litermeter pump that had the low flow. Once I put it back together it re-calibrated at 167ml/minute ;Happy. Spectrapure support was very helpful. They said it was not normal that the flow rate dropped to such a low amount, especially over a five meter horizontal distance. I will check the flow rate in a couple of months and hopefully it will not have such a variance.

- I started the Fauna Marin Amin amino acid additive a week ago. I started at half the recommended dose and will be increasing it over four weeks up to the recommended dose. So far it has not raised NO3 at all, still measuring around 8ppm plus or minus 2ppm.

The corals have really coloured up with deeper colours, especially the red monti which at one point was a pale pink. Now it is deep red. And the growth rate has picked up, as has the carbonate consumption. Nor sure what exactly did all this as I changed several things at the same time (bad habit!):

- Started dosing phyto (Easyreef booster).
- Reef Chili every other day
- PO4 dosing to bring PO4 up

I'm tending to think it is more the PO4 dosing... but it could be a combination of all three. In any case, I'm happy with the result so far and will continue with the three and keep a closer eye on the PO4 over time and not let it get that low again.

Stay safe everyone!
 
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Colours of coral are continuing to improve: deeper and more vibrant! As well as better polyp extension (though I'm not sure that means much) and increased growth...

I've been dosing the Fauna Marin Amin product (amino acids) for the past two weeks as well. So the combination of higher PO4 (NO3 is staying between 6 and 10ppm), Reef Chili every other day, phyto on a doser and the Amin is giving me good results so far.

To be monitored!
 
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For the past couple of months I've noticed that I'm changing/swapping the two DI canisters on my RO/DI unit more often. I'm reading the TDS of the RO water going into DI canister #1 and the TDS of the water coming out of the same canister. As soon as the water coming out of DI canister #1 shows anything other than 0 I move DI canister #2 to position #1 and the used DI canister is emptied and refilled and becomes DI canister #2.

Yesterday I was getting a TDS of 2 coming out of canister #1 after only about 380-400 liters (around 100G) of water was made since the last change.

This seems very low. I remember when I was filling the tank for the first time I was getting about 1,200 liters of water before a DI change...

I read somewhere that a 10" DI canister should take out about 3,800 TDS. My RO water going into the DI canister is measuring 3-4 TDS. Which means that I should be getting between 950 and 1,200 liters out before changing DI.

Something is off and I suspect that it may be the quality of the DI resin. After the first fill of the tank due to availability I purchased the Triton DI resin (the 5 liter boxes). I would have thought the Triton DI would be top quality?

I will order some of my previous brand of DI resin (Fauna Marin) and see if the culprit is poor quality DI resin.

Can anybody think of another reason this could be happening?
 

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