Hello,
Until recently I had a 28 Gallon tank and I did the PWC as follows:
20% every Wednesday + 40% every Saturday or Sunday.

I have now a 100 Gallon tank stocked as in my signature and would like to now what is recommended for frequency and volume for the PWC.

I did not perform any PWC for 1 full week and my water readings (Nutrafin drop test) are as follows:
Last week wednesday: PH 7.6 - Nitrit 0.0 - Ammonia 0.0
Today (Wednesday): PH 7.2 - Nitrit 0.1 - Ammonia 0.0

I am a bit worried about the drop in the PH value. Is this normal?
I can't test the Nitrates as the drops in the bottle are finished. I will have a new Nitrate test kit in about 10 days.

How should I go about tne PWC?
Btw, If I listen to my kids (8yo and 11yo) we should do it every day or possible 2 times or more a day........

Thanks for your advise,
Marc

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100 Gallon tank (work in progress)
2 x Fluval U3 filter + DYI CO2 + 40W 'Grolight' + 2x28W 'warm white'

3 Bala sharks + 2 Angel fish + 2 Black Mollys +1 Orange Platy + Plenty of Molly fry, baby's & teens

Egeria Densa, Cryptocoryne petchii "pink", Urticularia Graminifolia and African waterweed

When did you take the ph reading? A tank with plants can have a slightly higher ph at the end of the lighting period when the plants have been using up the CO2 in the water. Not sure how many of the plants you have in your tank. I notice very little difference in mine and they are heavily planted....before I added CO2 anyway.

Do you have a kh test kit? Have you ever tested the ph of your tap and also set aside some tap water and tested 24hrs later? This is good data to know. If you have some crushed coral, you can add some (very little) to help hold your ph steady but it would be good to know kh and the ph of your tap now and 24hrs later.

I change 50% of my water every week.

I still don't understand the point of weekly partial water changes in a heavily planted and filtered tank. But, to each his own.

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In a high tech tank with fairly high intesity lighting, CO2, daily dozed ferts it is actually a necessity to reset nutrient quantities.

Aside from that, it is just good practice I did before I went planted. Keeps your water safe and keeps the accumulation of dissolved solids that cause things like constant creeping (higher) ph, to a safer level.

I do 50% on mine as well,because I dose ferts and CO2,and feel its for the health of the tank.

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http://bountifulbettas.blogspot.com/

"Come to the dark side....we have cookies...and filters/heaters/and water changes!"

In a high tech tank I definitely agree with you. But in a low tech tank, i think the stability of limited water changes has great benefits.

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As does regular water changes. Any benefit of no water changes, can be met with just as many as doing regular water changes. I will never believe that tanks with little to no water changes will ever be healthier than one that gets. There are arguments on both sides of the fence.

Jr, you may be correct. Just presenting the other side

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In a planted tank low.no ammonia and nitrites are normal. But you can get an initial nitrate spike.

pH should be higher but sounds about right.

to me the best way to maintain a tank is to balance it out with live plants and to use peat moss in the substrate. The peat moss IME tends to keep hardness in line.


I do that and then do no water changes just replace evaporative losses. And have had thriving tanks for up to 9 years with descendants from the original cycle fish.

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

Why should ph be higher?

Hello marc...

You seem to have a lot of concern about your tank's water chemistry. I don't have the years of experience that some of the other folks on this forum do but, if you start and follow an aggressive water change routine of replacing a minimum of half the tank water every week, you don't have to worry about water conditions.

Large and frequent water changes keep the chemistry of the water in your tank stable and stability is the most important to your fish and plants.

If you do your water changes religiously, there's no reason to test your water parameters, you know they're "spot on".

IMO, tank keepers waste too much time messing around with water chemistry. By flushing a lot of clean, treated water thorough your tank, you guarantee a stable enviroment for your fish and plants.

My advice is, do your water changes and the fish and plants will be fine.

B

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Low Tech Water Building Keeper

Part of the nitrogen cycle is an increase in carbon dioxide which lowers PH.

In the case in one week pH went from 7.6 to 7.2 and nitrItes from 0 to .1.

So that is just a classic cycles.

With a planted tank pH should rise (just before lights out) because the plants are sucking out the cardon dioxide.

I also get a 1 day bump up of nitrItes to .1 then it drops down to 0 the next day.

So if pH has fallen and nitrItes bumped up perhaps one should stop adding food until both recover. At least that's what I do and get recovery in 2 days max.

My pH in my planted tanks is also much higher (8.4-8.8 (purple) on the api high range test kit.) But the 7.6 could be the max reading on the api pH (non high range) test kit. So possibily the pH was initially much higher therefore the pH drop is more pronounced.

So bottom line the pH drop indicates increased carbon dioxide.

Still just my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

That is essentially what I posted at the top of the thread. I never saw a drop of more than .2-.3 at the end of my lighting cycles before I started adding in CO2. I completely understand how CO2 affects a tanks ph. Mine swing a full point from pressurized CO2.


I just didn't understand your comment about how the ph should be higher.

Just my experience with a tank full of anacharis.

his and your mileage (and pH ) may vary.

worth at most .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

There are many bad things that build up in ANY tank. These include growth inhibiting hormones and dissolved organic compounds. Although a planted tank can handle fewer water changes than the equivalent unplanted tank, they still need them, and will do better with them.

In an unplanted tank all the bad things tend to correlate with nitrate, but since planted tanks remove nitrate, but not the other bad things, you can get false results that look better than they really are.

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Biologist-Professional Aquarium Care-Published Author (Aquarium Fish International Magazine)

Stocking has NOTHING to do with tank volume, it is all about water changes.

I disagree with this and hopefully you know with respect.

Plants are one of the most effective water filters so much so that industrial waste sites are cleaned up by enviromental engineers with both live and dried plants.

By contrast water changes at levels and intervals convienent to the aquariumist (10% weekly 30% monthly etc) will limit but not prevent changes to the environment.
Which is why unplanted tank have 100ppm of high nitrates plus algae problems and so on.

Additionally relying on water changes also relys on the condition of the replacement water making the tank suspectable to seasonal changes and the like.

By contrast plants with no water changes will reach a healthy, stable, and balanced state where both the fish and plants thrive.

All us lowly humans can do is screw up the environment.

But still just my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

Plants help, but they are not 100%. Yes, they are a great form of natural filtration, but they don't remove all the bad things that build up. They do not remove growth inhibiting hormones.

Yes, inadequate water changes will cause problems. If you have a nitrate concentration of 100ppm you are not doing enough water changes. Equating the problems with inadequate water changes to water changes in general is errored. A tank should get enough water changes to keep the nitrate concentration under 20ppm. My usual recommendation is weekly water changes, this frequency prevents the tap water from being too different than the tank water and causing certain problems. The amount will vary from tank to tank, minimum 25%, more if needed to keep the nitrate under control.

I agree that a planted tank may not need as large of a water change as an unplanted tank, but to consider water changes in a planted or unplanted tank as a negative thing is simply wrong IME.

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Biologist-Professional Aquarium Care-Published Author (Aquarium Fish International Magazine)

Stocking has NOTHING to do with tank volume, it is all about water changes.

Although I don't agree with everything you said, I can agree with most. But, I also think that plants are not the answer to all there is to a tank that doesn't get water changes. It may be an environment suitable for fish and plants, but I can argue the same for water changes. Water changes are not unhealthy. Yes, you may not have to deal with as much with topoffs if the water source is slightly screwed. However, those things the aquarists learns to work around and only the inexperienced will have problems getting it right in his/her tank.

As good as plants are at filtering, explain how you always state that plants drive up ph? Plants do not do this! It YOUR tanks this happens! I'm not talking about the daily up and down use of CO2 in the water by the plants. I believe it is from never getting the water refreshed and the TDS in the water just builds and builds, which will drive up ph over time. The plants can do a lot, but in the case of year after year without a water change, they are limited. Very few people that I have come in contact with either in person or the thousands on the internet forums deal with a ph that is as high as you have stated you have (8.5+), not to mention the incredibly high gh you've mentioned (35+). I can keep my gh at the same level it was 18 months ago (10) and I am on well water. Do frequent water changes and watch the level come back down to where it started straight from your tap. I will gladly let you borrow my TDS meter to test your water. Just my .02

Plants can use KH as a carbon source, which will actually drive the pH down over time. I have seen this happen in well planted tanks with no water changes. Eventually the pH was too low to register on test kits. The TDS may go up, but there has to be some KH there to hold pH up.

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Biologist-Professional Aquarium Care-Published Author (Aquarium Fish International Magazine)

Stocking has NOTHING to do with tank volume, it is all about water changes.

Actually I did use a wet/dry on my 55g which was just a wastebasket full of crushed oyster shells. in a 29 gallon I had a sump with chaeto only.

So on one tank yes on another no.

I did use the diy 2 part to maintain calcium,alk,mag on both tanks.

In both tanks nitrates and phosphates (salifert kit) were unmeasureable.

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden