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blackwater tank cycling?

anewbie

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1,339
It doesn't make sense to me. Since the pens are measuring EC (and not TDS directly) you should be able to derive the ppm TDS from the EC, full stop. 27/500 - 0.054. Is it close to 0.07? Yeah, but since it's a calculation and not a measurement, I'd want to know why the two values don't jibe.

You say the pen doesn't state the unit. OK, is there any online resource, or can you ask the company that made it?

If you care about precision and knowing whether the TDS is 25, 50, or 70, you should sweat the details, IMO. I'm all for inexpensive pens as long as you know what the output means. i.e., if it's inaccurate, do you know how, or by how much? Here's what I'd do personally (obviously up to you):
  1. Purchase a standard solution. 1413 uS/cm is the most common one. I usually verify against that and a lower one (23 uS/cm). Is that second measurement overkill? Maybe, but since I need to measure EC in the single digits, I want to be confident that it can measure precisely in that regime. And/or:
  2. Spend slightly more money and get a more precise meter. You can get an HM or Hanna meter for about $60.
If you want to use the cheap pens, I recommend doing #1.

In either case, you don't need to rely on the pen's TDS measurement if you know what the EC units are.

You don't have to do any of this, but if not, it's hard to say whether the TDS is "over the limit."



Possibly, or something else in tank. It's also likely a noisy number.

-B
I didn't explain well - the pen has modes - in tds mode it measures around 27 in ec mode it measure around 8. It comes with 2.7 ec solution which i use to calibrate the ec.
 

Ben Rhau

Apisto Club
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563
Location
San Francisco
I didn't explain well - the pen has modes - in tds mode it measures around 27 in ec mode it measure around 8. It comes with 2.7 ec solution which i use to calibrate the ec.
Unfortunately, I don't know how to interpret those numbers. Maybe it's 27ppm? But then I don't know what units the EC is, which is actually what the pen is measuring.
 

anewbie

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1,339
Unfortunately, I don't know how to interpret those numbers. Maybe it's 27ppm? But then I don't know what units the EC is, which is actually what the pen is measuring.
I'm pretty sure the tds is 27 ppm; but the displayed ec measurement is very confusing and the manual is more confusing. I have two tds pens and they are both giving 27-29 range; just can[t make sense of the ec measurement.
 

anewbie

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1,339
I now think the pen is reporting 70 micro/cm - is that too high - should i be doing water changes with pure ro water to try to lower it ?
 

Mike Wise

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I have 2 problems. First this is a high range meter so I can't tell how accurate it would be in a low range environment. The meter was made for hydroponic use where higher ranges are expected and the degree of accuracy is less important than in a softwater environment. Second I couldn't find a manual that gives the meter's specifications. Without those it's anyone's guess how accurate the meter is for aquarium use.
 

anewbie

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1,339
I have 2 problems. First this is a high range meter so I can't tell how accurate it would be in a low range environment. The meter was made for hydroponic use where higher ranges are expected and the degree of accuracy is less important than in a softwater environment. Second I couldn't find a manual that gives the meter's specifications. Without those it's anyone's guess how accurate the meter is for aquarium use.
Is there a meter (model/brand) you would recommend. Yea the manual lacks specs; i emailed support to ask them for range et all.
-
correction in that it does have range and stated accuracy - the stated accuracy for ec is 0.1 - which i think is 10 micro/cm
 

Ben Rhau

Apisto Club
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563
Location
San Francisco
According to the technical specs, the meter is accurate to within 0.1 EC, so +/- 100 uS/cm.

 

anewbie

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1,339
According to the technical specs, the meter is accurate to within 0.1 EC, so +/- 100 uS/cm.

Ok - i was confused by units - i thought it was in millie; either way it is not accurate enough for my application so is there a pen you recommend ? most of the ones i find are hydrophonics i don't see any accurate one for blackwater - maybe blue-lab ?
 

anewbie

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1,339
even hanna and milwaukee probes are going to be off by 10 microS; and they are $400 and $200 respectively.
 

anewbie

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1,339
I think the reason you were seeing 2.7 EC is because that's the calibration standard. Probably wasn't clear what was being displayed. For lower range EC and pH, many people recommend the <Hanna Combo meter 98129>. If you don't need pH, you can get <HM Digital COM-100>, which is cheaper.
I don't need another ph probe but the hanna you linked seems more accurate; the other is going to drive me crazy so i guess i'll bite the bullet (again) and get the hanna. My one concern with the hanna is longevity since the ph probes don't last very long esp if they get dry; i wish they had just an ec meter.
 

anewbie

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1,339
Ok in about 4 days i'll have the meter and will report new values. Sorry for the spam.
 

anewbie

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1,339
The acid arrived; 30% - added 5 1/2 ml and ph dropped from 6.67 to 6.19. WIll let it sit overnight and if stable will add a little more to get it below 6.19. Wed will add some more hatchet fishes and thursday when meter arrive measure ec.
 

anewbie

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1,339
ph rose to 6.44 over night; so i put in 4 more ml of acid and it is now reading 6.0; will wait 48 hours to see how it balances.
 

anewbie

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Messages
1,339
Weird; throughout the day the ph has risen - after adding 4 additional ml which sent the ph to 6.01; it has risen over 8 hours to 6.20. I'm not going to add any more acid for at least another 24 hours so i can measure the ec and see if it continues to rise over night. There is no rocks in the water but a ton of wood and leaves and a few test fishes. As of this morning the fishes (5 hatchet) seemed unaffected by the acid addition.
 

Ben Rhau

Apisto Club
Messages
563
Location
San Francisco
It sounds like you haven't been able to neutralize all of the carbonates. I'd recommend doing a water change and then measuring your baseline water parameters (EC/TDS and KH). If it's quite high, you may need to dilute it out first. Then, take water samples and do your pH lowering experiments outside the tank. See how that water behaves before scaling up.

For me, I had to drive the pH down to a pretty low number, at which point it took less acid to keep it there. However, you don't really want to do that with fish in the tank.
 

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