what the height of the power head?

[chimera]

layton/pies - thanks for the reply re: aluminium.

pies - the heat exchanger sits in the tank with pipes flowing to and from it to the radiator that sits external to the sump (with fan). no salt water goes near the radiator.

layton - so surely a stable ph indicates a good alkalinity???

thanks for your replies.

[jetskisteve]

i think none of us are helping with the powerhead height thingy! but on that note: I have'nt checked my ph for months either in fact i sent pies my probe :oops:

[lduncan]

A stale pH does not necessarily mean good alkalinity, but good alkalinity guarantees a stable pH.

The pH may not change because nothing is causing it to change (or any changes are cancelling each other out), your alkalinity could be anything in this case.

If your pH is changing rapidly or over a large range, your alkalinity is definately low.

So I see alkalinity as a more important parameter to test, you get two for the price of one, (which is not too common in this hobby) you know the value of your alkalinity, and, if this is within normal values, then you know your pH will be right.

Layton

[chimera]

makes sense - im still learning with marine so i think i'll test for both

[Pies]

Layton - I am not sure that your advice on measuring alk not PH is correct. I would have thought that because you are using 2 part Calcium soultion that keeping an eye on PH would be far more important. Alk does represent the stability of PH however if your PH was wrong, or has been increasing or decreasing slowly over time, then high alk will just help hold it at this paramater. With the addition of additives (CA, Buffer, Kalkwasser, Freshwater & saltwater water changes + In your case sugar, Zeovit & Vodka?) all of these things can have an effect on PH. As does lighting. Knowing what your PH is doing and how much its fluctuating is important but perhapps not nessessary. For example knowing my PH has allowed me to add kalkwasser at optimal times to ensure more stability of my PH during lights off. Your 2 for the price of one is not accurate though as the PH may be off or changed by the things mentioned above, ALK will not show you that PH has changed or what PH is.

I don't agree that PH testing is something you shouldn't do, but I understand your logic. I don't think its good advice to reccomend that it shouldn't be done. I do agree that alk is a VERY important paramater and should be tested regualry though. JetSkiSteve thanks for the probe!

Chimera - Saltwater gets EVERYWHERE...

[lduncan]

Alk does represent the stability of PH however if your PH was wrong, or has been increasing or decreasing slowly over time, then high alk will just help hold it at this paramater.

Think about this, if Alk represents stability of pH, then if your alk is always high, how can pH decrease slowly over time? It's not true.

The only calcium additive I use is Kalk (no 2 part or anything). Alkalinity (as measured by test kits) gives the concentration of Calcium Carbonate/hydrogencarbonate.

Calcium HydrogenCarbonate has an inherent pH of around 8.29, which is fixed by standard chemistry, it can't change.

Calcium HydorgenCarbonate is one of the results of adding Kalk.

So if your alkalinity test kit is measuring calcium hydrogencarbonate, then your tank is likely to be within correct pH range of around 8.3.

When alk is low however the resistance to changes in pH is less responsive, so larger pH drifts may be seen with lighting cycles.

When alk is high, changes in pH can be countered more quickly, so you will see less of a swing with lighting cycles etc.

The way alk is measured, it guarantees that if the pH drifts away from 8.29, the alkalinity will pull it back up, or down, to this value. How quickly it does it depends on how high the alk is.

I'm not saying don't test pH, just saying that it's one less test to do, assuming your alk is within normal range.

Layton

[Pies]

Layton - You should read this - http://www.advancedaquarist.com/issues/ ... 2/chem.htm

A good explination of PH for you as I think your quite a bit off the mark. Gives several examples of PH problems not related to low ALK.

FYI - Just tested my water - ALK = 8.0 & PH = 8.27

Pies

[reef]

Interesting subject.

I give up worrying about my ph as I have found that if you don’t calibrate you ph meter weekly then you aren’t getting a accurate reading as the probe gets dirty and calcium builds up.

Also most ph meters aren’t that accurate as they don’t have a temperature meter attached as you have to read both together to get a correct reading as temperature will affect ph.. A good ph probe cost over $300 and they only last 12 months.

My tank is about 7.80 in the morning and 8.10 during the day. I have never been able to get my ph above 8.30 .

I have seen people claim that there ph is 8.40 and higher. This may be correct or there is something wrong with there probe etc.

The other thing that affects the ph reading when using probes is other electrical devises as when I had VHO lighting every time I turned them off the ph would go up.

So the questions is,

How accurate are all these readings on ph.

Best to use the ph as a guide .

[lduncan]

Pies, all those problems in that article, are either cuased by low alk, or result in a low alk. There is even a problem entitled "Low pH due to Low Alkalinity". The artical accually points out that alk will "crash" in another case (but is silent on others)

My reasoning comes from standard stage 1 chemistry. I'll post some equations and a graph or two to show you how alk an pH are related. And why alk will pull pH towards 8.3.

Maybe something for the next newsletter.

Layton

[Pies]

Accuracy - I am sure these devices are very accurate, not sure what reef means about using them as a guide? I take my readings as gossipl, I am sure they are within a few points of spot on.

As for others claims of high or low PH, if they are using PH test kits (salifert, Hagen, Red Sea or whatever) then they could be reading anything. Those things are so wildly out of wack its not funny, use these tests as a guide.

My probe is in my sump in the dark, its as clean as the day I put it in. I have re-calibarted it once but it detected the fluid 7&10 perfectly. They claim the probes last 2-3 years. Many on UR claim use of over 5 years without issue.

I give my Pinpoint monitor 10/10. If I paid 100x more than I did pay for it, it would still be one of my best purchases! Also works in fresh water!

NOTE: Electronic PH monitors made eric Bournemans list of 'reef keepers must haves', and Eric knows stuff.

Piemania

[reef]

Accuracy - I am sure these devices are very accurate

They are about as accurate as picking the winning teams in the super 12 every week.

Ph probes in general are not accurate especially ones without temperature compensation. And should be used as a guide and not gospel.

Pies your ph probe might be saying 8.29, but with allowing for temperature the ph might be 8.20 or 8.40

When calibrating the probes . the calibration solutions needs to be heated up to 25C or what ever the solution says. otherwise the meter will not be calibrated correctly.

To get very accurate readings, a very good quality ph meters would be in the thousands,

Spoke to a chemist friend, who advised me that the ph readings are only as good as the probe. and advised me to get lab grade probes.

also you have to check that the probe matches the meter voltage.

Still these ph meters made for the aquarium trade are still useful for the hobby as do we really have to worry if the ph is 8.10 or 8.30.etc , I think not.

[Pies]

Pinpoint are temprature compensating and yes you must warm the calibration fluid to the temprature of your tank prior to calibrating its use.

There are zillions of PH monitors out there all claiming 1/100 of a PH for accuracy, if they wern't accurate to within 1/100 then the would jsut advertise a different accuracy level.

These units ship with lab grade PH probes, you can buy cheaper probes. Cheap are about $30.00ea, expensive lab grade probes are $50, thats USD.

So if my monitor shows 8.29 for PH I am confident that its between 8.28 and 8.3

If they were not accurate people would not use them. Personally I would like to know if there was a difference of .2 in PH. 8.3 is good, 8.5 is a problem. 7.9 is low, 7.7 is very low. I personally am trying to stablise my tank paramaters, including PH. This is the only way to do it.