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EI extended water change period.

thevictorian

Seedling
Joined
11 Dec 2015
Messages
15
Location
bristol
Is it ok to extend the period between water changes when running the EI method? Normally I stick to the 50% once a week but am hoping extending that to once a fortnight won't be a problem. I run normal doses plus 25% increase.
Plant growth is good but it's more the fish and shrimp I'm worried about al though dnot think i hAve ant thing to sensitive. I have cherry plus dwarf cory, pencilfish and glowlight danios.

Thanks in advance.
 
Hello

I wouldn't advise cutting down on water changes, especially if you're running EI + 25% and injected CO2. If you want to cut down on WC I'd suggest cutting back on EI, lighting time and injected CO2 period. Observe and see what happens.

Are you seeing any issues with your fauna?

I have 2 types of shrimp, 3 types of corydoras and 2 types of tetras. EI + 50% (6 days pw), 65% weekly WC with very hard tap water. Fauna are not showing any negative effects.
 
Think my tablet had a spasm during the last sentence.

I haven't actually stretched them out yet and am only 1 day overdue. TBH its only something i'm trying to see if its feasible as things are getting a little hectic and i'm not always about on waterchange day like today.
Its took me a while to get things working in sync but its really took off since I have, so don't really want to change the dynamic unless it won't do any harm.
 
A few days overdue won't be detrimental.

Maybe do a bucket worth of WC if it's quick. Sometimes I'll do 3 small buckets (25l each) over a week if too busy to do the full 65% on WC day.

Whatever works for you.
 
Best to reduce ferts and lights slightly if you want to stretch out water changes. Otherwise you could get toxicity from various dosing.
 
Is it ok to extend the period between water changes when running the EI method? Normally I stick to the 50% once a week but am hoping extending that to once a fortnight won't be a problem. I run normal doses plus 25% increase.
Plant growth is good but it's more the fish and shrimp I'm worried about al though dnot think i hAve ant thing to sensitive. I have cherry plus dwarf cory, pencilfish and glowlight danios.

Thanks in advance.

If you are trying to create more stable water parameters for the shrimp, waiting 2 weeks between 50% water changes will have the opposite effect.

The most any nutrient can build up doing 50% water changes is 2x the total amount dosed in between them. (this assumes zero plant uptake)

For example EI nitrates is 7.5 ppm 3x week, with a 50% weekly water change. That is 22.5 ppm dosed between water changes. Therefore, the most you will ever have is 45 ppm (again this assumes zero plant uptake for simplicity's sake) So theoretically you are going from 45 ppm down to 22.5 after a water change.

But stretch that out for two weeks, and you are going from "potentially" 90 ppm down to 45 after a water change. Big difference.

Like others have said, if you are going to do bi-weekly water changes, best to cut EI in half or thereabouts.

If the main concern is stable parameters, even better would be 33% weekly water changes with reduced EI. The most you can build up changing 33% is 3x the total dosage between water changes. So there is potential for a greater build up of nutrients, which you can adjust for, but a smaller swing in parameters after each water change.
 
Best to reduce ferts and lights slightly if you want to stretch out water changes. Otherwise you could get toxicity from various dosing.

That is what I was worrying about really a build up of something that proves harmful but wasn't really sure how long such a build up would take.
 
If you are trying to create more stable water parameters for the shrimp, waiting 2 weeks between 50% water changes will have the opposite effect.

I was more thinking how long I could go without impinging to much on water quality but it probably best to just make sure I stick to my normal weekly routine.
 
Well I have to disagree with many of the answers the OP has received. No problem in having doses of 90 ppm of whatever fertilizing inorganic compound. That is not the problem. I has been proven by Clive or Tom that NO3 or PO4 in very high doses do not become toxic for fauna.

The problem with cutting down the water changes is the accumulation of waste that may poison your fish due to DOC (dissolved organic compounds) released as waste product from both plants and fish. These DOC are degraded and release NH4 and other poisoning compounds that are really toxic for fauna and may also trigger algae blooms.

If you want to cut down on water changes with the same growth rate you have now, the only thing I can advice is to buy some purigen and toss it in your filter. That would give you some more room before the water change is needed.

Anyway, I would not go for that alone and I will follow roundasapound advice. Cut down on lighting, but not on photoperiod. Cut down on light intensity (release the foot from the gas pedal).

Cheers

Pedro
 
If I extend my water changes to much more than a week (due to no spare time) I start to get BBA appearing on plants and hardscape, which is a symptom of excess DOC and this is despite Purigen.

What I tend to do, if I know I am not going to be able to do a weekly water change, I knock a couple of hours off the light and CO2 times and reduce the EI dosing a tad which means I can go more than a week without having BBA (and GSA) rear their heads.
 
What I do on holidays when I know I will be at least 15 days away is to disconnect 2 out of my 3 LED bulbs keeping everything constant except that I dose 1 week equivalent EI at once. Normally when I get back, there is a little GDA on the glasses, but that is all. CO2 is normally untouched.
 
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