Low pH and dosing supplements

[Mindi]

I have a mixed reef with water volume of 500 litres. I use Randy 2 part Recipe 1 ( the cooked soda one) and it works well for me, but I have ongoing low pH. Have calibrated the meter and bought a Salifert kit to crosscheck and 7.9 it is...and stays. Very little diurnal change if any. I have done the inside / outside aeration test and strangely both produced an increase in pH...but the outside fresh air got it to 8.2 while the inside air got an identical sample to 8.1. I think I have a number of options

1. Get over it and accept 7.9
2. Aerate the tank even with inside air..??
3 Switch from recipe 1 to Limewater.

I would quite like to consider limewater, but having read the articles I cant find any dosing calculations..? I currently dose 45ml (of recipe 1) parts 1 and 2 daily. What dosing volumes of settled limewater would approximately replace this..?...so that i can manage the switch with minimum shock to the system

Many Thanks..........John (Australia)

ps...should have said my Alk is 3.5 meq/l and Calcium 430 ppm. Could ramp up the Alk to raise pH but not sure how wise that is.

pps...sorry have just thought of using the dosing calculator which tells me I am consuming 0.17 meq/l daily ...which in turn would require 2.1 litres of limewater as an alternative to my 45 mls of recipe 1. So it is not a role for my dosing pump but would have to be part of my top up process.... so I think that really answers my question. Maybe I just get happy with 7.9

 

[cjd]

PH is a number that many reefers get to involved in chasing. Assuming that your ph probe and or test kit is giving you an accurate reading , 7.9 isn't bad . All of my reef tanks seem to settle in and run in that range . Only one time did I have a tank that ran 8.2 and that is when I dosed kalkwasser on a continues drip to match my tanks daily evaporation.
I still dosed alk and cal separately to make up for what my tank consumed daily as the kalk alone wouldn't keep up .If you decide to go that route, max dose is 2 teaspoons per gallon of freshwater . Not because you can overdose with adding more , because that is the max that will dissolve in the rodi water . Any more and you are wasting product. If you are able to pull outside air with your skimmer that is a great option as well , if that is not possible add a CO2 scrubber to the inlet of your skimmer greatly reducing the amount of CO2 in the aquarium which is usually the cause of lower PH . Just a side note that the amount pulled from the skimmer air intake relies on how much air draw that skimmer has . If the surface agitation exceeds the air intake of the skimmer you probably wont see that much of a difference.
Adding products that buffer ph is only a temporary solution and end up throwing alkalinity and calcium out of whack causing other issues. If you really want to raise the ph of your reef I would definitely look into dosing kalk continuously or adding a CO2 scrubber .

 

[AdamNC]

After chasing it for 2 years I gave up and accepted 7.7-8.1 for my day/night swing. Without a temporary supplement the lowest I go is 7.68 and the highest averages about 8.08-8.1.

 

[Randy Holmes-Farley Verified Community Expert]

My DIY two part recipe is about 47 times more potent than limewater. So if you dosed 1 ml per day of each part of the two part, a similar dose is 47 mL of limewater per day.

That said, it will only be an approximation since you may not get saturated limewater, and the demand rises as pH rises.

 

[Mindi]

Thanks everyone

 

[Mindi]

Have run an oversized airline out into fresh air for the Deltec skimmer. Hoping this will help. The more I think about it the less impressed I am by a new house with airconditioning and no fresh air makeup at all. Sure we open doors and occasionally windows but this experience suggests to me that we are breathing (or re-breathing) lots of CO2. Will take daily pH readings at the same time for a week or so to see if there is any effect with fresh air into the skimmer.

 

[JoshuaBrown]

Update?

 

[Mindi]

After 4 days have only moved 500 litres from 7.9 to 8.0. Expect it to be slow, but seems to have had a small effect.

 

[Randy Holmes-Farley Verified Community Expert]

After 4 days have only moved 500 litres from 7.9 to 8.0. Expect it to be slow, but seems to have had a small effect.

The balance is between tank top aeration with high CO2 air and skimmer aeration with lower CO2 air.

 

[Mindi]

I have to retract that last post about moving from 7.9 to 8.0.... was deluded. After a week it is still at 7.9 but I am not surprised at that, with no realistic means of calculating the effect of the outside air I am prepared to go with the thought that it is a step in the right direction but it may be so small that it takes weeks to shift 500 litres enough to measure. See RHF comment above..too true, 10 sq ft of surface area doing gas exchange with poor air while the skimmer is doing good things below. Patience.
Will keep monitoring and post an update when I measure something starting with 8.

 

[cjd]

I said that in the first post

 

[Randy Holmes-Farley Verified Community Expert]

I actually think the effect of aeration changes of any kind will be pretty well maxed out in a couple of days.

 

[Mindi]

I said that in the first post

yep...but the difference is that I now understand it.

 

[Mindi]

More learning and some improvement
This is all tragically unscientific ...but... Managed to create a fresh air path through the area of the tank with a couple of open windows on a quite still day...so some, but limited, fresh air movement past the tank. Used a stream pump to move the surface and after a little as half a day the reading moved from 7.9 to 8.0, and the 8.0 was repeated several times in the following hours after a calibration check. So decent fresh air , on that basis, is more effective aeration method than fresh air direct into the skimmer...which seems insufficient to even register a nett change after a week. I am sure that this is what people have already said, but this very limited trial confirms that. If I have it at 8.0 I am moving on .
Thanks for the contributions..appreciate it very much. Have looked at a nice easy DIY CO2 scrubber but so far havent found a good source of Soda Lime. Will still pursue this but I think it is no longer so important.
John

 

[Mindi]

Last post on this. Lots learned, in my case the occasional opening of a nearby window for about 3 -4 hours and 3 or 4 times a week has raised my afternoon pH from 7.9 to 8.1. while 7-10 days of outside air into my skimmer had no visible effect. Have maintained some surface movement to help the gas exchange, but in my situation fresh room air was much more effective than fresh skimmer air. So two weeks on I have steady 8.1 which is a good result.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the update.

Happy Reefing.

 

[Mindi]

Final final update.

To recap ... have had persistently lower than ideal pH reading at a very consistent 7.9 at midday for months. I run Randy (recipe 1) 2 part.in a 520 litre water volume. Acknowledge that 7.9 is not BAD but wanted to lift it a little if I could.


Step 1. Did the inside and outside aeration test and I clearly have an inside CO2 problem in a fairly new hermetically sealed house. Very clear result.


Step 2. Piped outside air to my skimmer intake( yes I drilled a hole in the wall) ...used an oversized tube only stepped down at the skimmer to reduce friction losses. This was a total fail...a week of running and still on 7.9. I am still surprised at this.


Step 3. Opened a window before and after the tank and improved surface agitation. This quite quickly ( < 1 day) raised it to 8.0 but no higher, and it was really just getting to 8.0 and dropped back when had to close the windows.


Step 4.... CO2 scrubber...Bought a 1 litre food container, drilled lots of small holes in the bottom, and a big jar of medical Soda Lime. Half filled the food container, hung it in the cabinet near the skimmer, and ran the air supply line into a hole in the lid. Re-tested after three days again at midday. Meter quickly went to 8.2.


I am very pleased at this result, but really don’t understand how it is this effective as CO2 only makes up 0.5% of air. But there it is..! outside air fail, fresh air draught sort of fail/pass ... DIY CO2 scrubber...Big Pass. In my case it is actually the easiest of the three attempts to do. Should have done it first...? I don't know how long 500mls of Soda Lime lasts but 5 litres cost me $60 at a Medical Supplies place.

 

[saltyfilmfolks]

Ummm. I'm kinda a simple man. But how much coral do you have in the tank and are you running a refugium or ats?

 

[Mindi]

I have mainly LPS about 15 or so, yes I have just started a refugium but it hasn't got much happening yet..what is ATS..?

 

[saltyfilmfolks]

Algae turf scrubber.
Both serve to pull co2 out of the water.

It seems like you've gone through a lot to pull co2 out to get ph up.

I've got none of that stuff but have a lot of coral and a large refugium. Even in winter with the gas heat on my ph doesn't get below 8.