Phosphate and alkalinity relationship need help to understand

[Gogo007]

Hello every one its long story but i will try to make it short

My tank is 200l mixed reef
No3 zero @Red Sea and salfert teat kit
Po4 used to be 0.04 to 0.06 with hanna ulr
Kh 8.4 with hanna
Ca 435
Mg 1380

From 4 days ago i came back home i see the corals is show some kind of stress and the colors are not the bright its going to be little brownish .. i tested my water and chocked the phosphate reading is 0.5 ppm and alkalinity 9.4 dkh .. i linked the po4 spike to activated carbon which is the last thing i added to the tank and yes it was it after i socked some in ro water and tested it came back with 2ppm! And i linked the kh spike to high po4 stressed the corals and stoped consuming my dosage i stoped the dosing and used lanthanum to get the po4 down to first day was down to 0.25 next day get it to 0.15 and dosed more sudden drop to zero

I prepared some water same day and changed 15 liter

Next day i lost my conffiti acropora !! It was showing stress when i changed water ..

My question is does kh really could be stopped to be consumed if po4 is high

Second how many days it will take to get my kh consumption back to normal

And if there is any thing i made incorrect let me know so next time i do not do it again i was going crazy fear to lose my pricy corals but looks like my actions was not that good

 

[Gravity]

I don’t think there is a direct correlation between them. High phosphate could reduce coral growth and reduce KH consumption. Or if the corals were stressed by something else it could cause KH and PO4 to increase but it sounds like the RO water was the main issue.

phosphate removers will also generally consume some alkalinity. So you may be able to run GFO or dose more lanthanum to reduce both.

 

[SPitts6654]

Po4 usually doesn’t spike like that, it’s usually a steady climb over time. I’ve never heard of carbon driving up Po4...

As for the Alk, if you’re doing a steady does and something upsets the coral, they may reduce uptake and drive your Alk up if you’re not monitoring and adjusting for it. As for how long it will take to come back down, depends on how much they consume in a day. My tank will consume 1 dkh in just over a day without dosing.

 

[Gogo007]

I don’t think there is a direct correlation between them. High phosphate could reduce coral growth and reduce KH consumption. Or if the corals were stressed by something else it could cause KH and PO4 to increase but it sounds like the RO water was the main issue.

phosphate removers will also generally consume some alkalinity. So you may be able to run GFO or dose more lanthanum to reduce both.

Phosphate was related to activated carbon i searched for that and i got to that coconut carbon is activated with phosphoric acid

The ro water is good. As tds is about 2
And i am ordering new filter elements in the ways

 

[Gogo007]

Po4 usually doesn’t spike like that, it’s usually a steady climb over time. I’ve never heard of carbon driving up Po4...

As for the Alk, if you’re doing a steady does and something upsets the coral, they may reduce uptake and drive your Alk up if you’re not monitoring and adjusting for it. As for how long it will take to come back down, depends on how much they consume in a day. My tank will consume 1 dkh in just over a day without dosing.

I am sure about the po4 in carbon i check the ro water with hanna checker and it shows 0?02 and when i put the carbon in water it show 2ppm ! My alk was steady with dosing 10ml of redsea alkalinity solution per day and start spike after phosphate comes up

 

[SPitts6654]

I am sure about the po4 in carbon i check the ro water with hanna checker and it shows 0?02 and when i put the carbon in water it show 2ppm ! My alk was steady with dosing 10ml of redsea alkalinity solution per day and start spike after phosphate comes up

I’d speculate that your RO test wasn’t apples to apples to the volumes used in your aquarium.

Carbon is pretty widely used in this hobby and a quick google search shows yes, a few have speculated it caused a very slight increase Po4 and just as many speculating it decreased Po4.

Unless you’re using some cheap carbon that isn’t intended or aquarium use, I’d be looking for a different source of the Po4.

10ml of Alk is a pretty low dose, so it may take a few days to burn off 1 dkh.

How old is your tank?

 

[Gogo007]

I’d speculate that your RO test wasn’t apples to apples to the volumes used in your aquarium.

Carbon is pretty widely used in this hobby and a quick google search shows yes, a few have speculated it caused a very slight increase Po4 and just as many speculating it decreased Po4.

Unless you’re using some cheap carbon that isn’t intended or aquarium use, I’d be looking for a different source of the Po4.

10ml of Alk is a pretty low dose, so it may take a few days to burn off 1 dkh.

How old is your tank?

Yes this activated carbon was not for aquariums its for water treatment. .. was my mistake to trust local fish store about it .. my tank is 6 month old .. yes 10ml is not much dosage per day but the problems is thay po4 is left in water for 4 days or more and lets say this 1dkh up is result of 3 days or 2 days dosage withno consumptions ... My question is what is might be more deadly the fast swing in po4 up and down or excess lanthanum chloride dosage ?

 

[SPitts6654]

If it was all over a matter of days it may cause a little stress, but I wouldn’t think you would see a lot of die off unless there was already something else stressing them before. The problem with the 0 Po4 is the dinos that may follow.

If your worried about the excess LC, just do a big water change and the work on getting a little Po4 back in the tank.

 

[Randy Holmes-Farley]

I am sure about the po4 in carbon i check the ro water with hanna checker and it shows 0?02 and when i put the carbon in water it show 2ppm ! My alk was steady with dosing 10ml of redsea alkalinity solution per day and start spike after phosphate comes up

That is a poor test that plagues the hobby with what seems logical, but is inherently flawed.

I discuss it here:

Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both

Foods are by far the most important source of phosphate in most aquariums. In considering whether sources of phosphate other than foods are important, one must carefully look to the actual amounts involved to determine whether other sources are even worth trying to minimize.

reefs.com

The same sort of calculation applies to analyzing other phosphate issues, such as the GAC in scenario three. The issue of finding “high” phosphate in GAC soaked in fresh water was frequently quoted as a reason to use one or the other brand of GAC, and probably still is. But simple analysis as shown above for the food rinsing puts the lie to this being a big problem.

One needs to consider how much GAC one will really use in the aquarium and how often it is added in order to interpret how important the added phosphate is. A typical recommendation might be 1 cup of GAC per 100 gallons of aquarium water, and to change it in 4-6 weeks. Let’s assume we detect 0.5 ppm phosphate when a teaspoon is placed in a cup of water, and we get scared by the dark blue color during the test. Is this reasonable? That 0.5 ppm from a teaspoon in a cup of water translates to 0.015 ppm phosphate when a cup is used in 100 gallons.

That 0.015 ppm may be significant, being a typical target concentration level for reef aquaria and amounting to about half to a twentieth of the amount added daily in foods, but remember, it is used for 4-6 weeks. During those 4-6 weeks before the next replacement, foods add 50-700 times as much phosphate. So while it is not unreasonable to look for another brand of GAC, to blame phosphate or algae issues in the aquarium on its use would stretch credibility because it is a very tiny portion of the total phosphate being added.

 

[Gogo007]

That is a poor test that plagues the hobby with what seems logical, but is inherently flawed.

I discuss it here:

Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both

Foods are by far the most important source of phosphate in most aquariums. In considering whether sources of phosphate other than foods are important, one must carefully look to the actual amounts involved to determine whether other sources are even worth trying to minimize.

reefs.com

The same sort of calculation applies to analyzing other phosphate issues, such as the GAC in scenario three. The issue of finding “high” phosphate in GAC soaked in fresh water was frequently quoted as a reason to use one or the other brand of GAC, and probably still is. But simple analysis as shown above for the food rinsing puts the lie to this being a big problem.

One needs to consider how much GAC one will really use in the aquarium and how often it is added in order to interpret how important the added phosphate is. A typical recommendation might be 1 cup of GAC per 100 gallons of aquarium water, and to change it in 4-6 weeks. Let’s assume we detect 0.5 ppm phosphate when a teaspoon is placed in a cup of water, and we get scared by the dark blue color during the test. Is this reasonable? That 0.5 ppm from a teaspoon in a cup of water translates to 0.015 ppm phosphate when a cup is used in 100 gallons.

That 0.015 ppm may be significant, being a typical target concentration level for reef aquaria and amounting to about half to a twentieth of the amount added daily in foods, but remember, it is used for 4-6 weeks. During those 4-6 weeks before the next replacement, foods add 50-700 times as much phosphate. So while it is not unreasonable to look for another brand of GAC, to blame phosphate or algae issues in the aquarium on its use would stretch credibility because it is a very tiny portion of the total phosphate being added

That is a poor test that plagues the hobby with what seems logical, but is inherently flawed.

I discuss it here:

Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both

Foods are by far the most important source of phosphate in most aquariums. In considering whether sources of phosphate other than foods are important, one must carefully look to the actual amounts involved to determine whether other sources are even worth trying to minimize.

reefs.com

The same sort of calculation applies to analyzing other phosphate issues, such as the GAC in scenario three. The issue of finding “high” phosphate in GAC soaked in fresh water was frequently quoted as a reason to use one or the other brand of GAC, and probably still is. But simple analysis as shown above for the food rinsing puts the lie to this being a big problem.

One needs to consider how much GAC one will really use in the aquarium and how often it is added in order to interpret how important the added phosphate is. A typical recommendation might be 1 cup of GAC per 100 gallons of aquarium water, and to change it in 4-6 weeks. Let’s assume we detect 0.5 ppm phosphate when a teaspoon is placed in a cup of water, and we get scared by the dark blue color during the test. Is this reasonable? That 0.5 ppm from a teaspoon in a cup of water translates to 0.015 ppm phosphate when a cup is used in 100 gallons.

That 0.015 ppm may be significant, being a typical target concentration level for reef aquaria and amounting to about half to a twentieth of the amount added daily in foods, but remember, it is used for 4-6 weeks. During those 4-6 weeks before the next replacement, foods add 50-700 times as much phosphate. So while it is not unreasonable to look for another brand of GAC, to blame phosphate or algae issues in the aquarium on its use would stretch credibility because it is a very tiny portion of the total phosphate being added.

I do understand your concern about food gives more po4 .. i may be used too much GAC ..also i will not use this type again maybe i will try high quality brand maybe purigen next time ..thank you for the mentioned topic and thank you for your kindly reply Mr Randy