The Planted Tank Forum banner

1 - 20 of 22 Posts

·
Registered
Joined
·
64 Posts
Discussion Starter · #1 ·
I did a 1/3 water change on Friday to get the TDH 240ppm I only got it to 255ppm this morning I checked it and it is 270ppm. What is causing this? I feed the fish once a day sparingly. I am trying to combat some algae by not dosing for a week.
 

·
Registered
Joined
·
3,020 Posts
Tds? Not sure what tdh is though.

How many fish do you have? What species? What size tank? Lots of plants?
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #5 ·
Cleaned canister filter 3 weeks ago. And removed loose debris when I did last water change on Friday. I do have 2 pieces of driftwood. The tank has been set up for 10plus years. I also dose co2 and Keep drop check green.
 

·
Premium Member
Joined
·
606 Posts
Are you topping off the tank with tap water?
 

·
Registered
Joined
·
1,505 Posts
Did you do the 1/3 water change with RO or tap? What ppm TDS is your tap?
What you are experiencing is a process of balancing the mineral content of the substrate with the tap. This is why the readings are slowly returning back after water changes. At one point this process will level up and get stabilized. That is the whole point of keeping good water column parameters. Topping up the aquarium causes accumulation and deterioration.
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #9 ·
My tap is 180 ppm. My water change was done with tap water. I stopped dosing on last Thursday and the plants seem to be growing better with no algae on new growth. My tank was 257 ppm tonight. I plan on doing a water change on Thursday and start dosing Friday morning.
 

·
Registered
Joined
·
11,721 Posts
Well, the dissolved material has to come from somewhere.
Most common sources (some have already been covered, but I will list them anyway):

Adding things to the tank, especially fertilizers, minerals or similar materials including pH altering products. Some products like this do not dissolve well, and keep dissolving for a few days after being added to the tank.

Adding fish food (takes a lot to make a change in TDS)

Something in the tank dissolving. Almost always this is calcium carbonate based material such as limestone (substrate, sand, rocks) coral or sea shells (whole or ground up into any size pieces) or other rock based product that dissolves.

Something lingering in the tank, freshly exposed. Perhaps buried fertilizer tablets, or an old 'food pyramid'.

I would do another water change, but not start dosing yet. Lets see if the same thing keeps happening.

Are all the other parameters stable? GH, KH, pH?
 

·
Registered
Joined
·
11,721 Posts
Water in an aquarium has minerals and salts dissolved in it. All these thing can be measured as TDS, Total Dissolved Solids.
When water evaporates, the minerals and salts stay behind. Now there is less water so the minerals and salts are more concentrated. TDS is higher.

You can top off with tap water. Tap water generally has minerals and salts. When you add this to a tank, to top off a tank where water has evaporated, this adds more minerals and salts. Then more water evaporates, TDS rises more.
Each time you do this there are more and more minerals and salts added to the tank. TDS keeps rising.

You can top off with water that has almost no minerals and salts. Reverse osmosis, rain water, and distilled water have almost no minerals or salts. When you top off the tank with this sort of water the TDS concentration drops down to almost as low as it was before any water had evaporated. The rise in TDS is so low you cannot read it with hobby level test kits. You could keep on topping off for a long time before you can see the rise in the test results.

This is very important to the livestock in the tank.
Fish regulate the levels of water, minerals and salts in their cells very carefully. When the TDS in the tank water is lower than the fish are accustomed to more water enters the fish cells, and the fish metabolism needs to work harder to get rid of it. When the TDS in the tank water is higher than they are used to their metabolism gets used to not having to work so hard. However, fish take in the minerals they need from the water. Certain fish evolved in water with very low mineral levels, so their body is very good at taking the minerals out of the water. When there are more minerals in the water (harder water) than they evolved in they still take out minerals from the water, and hold them in their body. They can hold more minerals than are good for them. Cardinal Tetras are one fish where this has been proven. They can die of excess calcium in hard water.

So, lets say you have been topping off with tap water, adding minerals each time. TDS is higher than the tap water. Then you do a water change with softer water (lower TDS). Gradually, as the TDS has been rising over several weeks or longer, the fish have been getting used to the harder water. Now, suddenly, the TDS is lower, and the fish metabolism has to ramp up to the level required to keep the water, minerals and salts in their cells in the right balance. The fish have a hard time doing this, and may not be able to remove all the excess water. This leads to dropsy.
This may be one reason why fish have a hard time when you buy new fish and add them to a tank with different water than they were used to. They can handle the higher TDS water (within reason), but the lower TDS water is harder to handle.
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #14 ·
Did 1/3 water change with tap (TDS 168ppm) the tank had a reading this morning of 249ppm. Is it normal not to be close to the tap water after such a large water change?
 

·
Registered
Joined
·
11,721 Posts
Do some math:
(TDS of tap x % in the finished water change) + (TDS of tank x % in the finished water change).
Example:
(180 x .33) + (257 x .66)=
59.4 + 169.62=
229.02

The concept is right:
When you do a water change the end result is somewhere in between.
Perhaps the starting TDS had gotten higher (I used a value posted up above in this thread).
Perhaps the 1/3 water change was more like 1/4.

The fish are happier with smaller changes in the TDS.
I would keep on doing smaller water changes, once or twice a week for several weeks. This gives the fish time to adjust to the lower TDS.
Do not do one giant water change that drops the TDS all in one go.

While you are working on this, continue to monitor the parameters that tell you about the fertilizer levels (whichever tests you have). You may have to start dosing before the TDS is down where you want it. If so, perhaps 1/2 doses or even less.
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #16 ·
I will test the water tonight. The plants seem to have less algae on the leaves since I stopped dosing last Friday. The plants have some new growth as well.
 

·
Registered
Joined
·
1,505 Posts
Did 1/3 water change with tap (TDS 168ppm) the tank had a reading this morning of 249ppm. Is it normal not to be close to the tap water after such a large water change?
If you changed 1/3 with tap at 170 and got 250 as a result then your aquarium before water change was 290.

1/3 water changes with 170 tap
290 -> 250 ( - 40)
250 -> 223 ( - 27)
223 -> 205 ( - 18)
205 -> 193 ( - 12)
193 -> 185 ( - 8)
185 -> 180 ( - 5)
180 -> 177 ( - 3)
177 -> 175 ( - 2)
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #18 ·
If I have root tabs in my gravel. How do I flush the nutrient out of the gravel? I think I put some root tabs in the gravel in January. I used some tabs I made with Capsules and osmacote.
 
1 - 20 of 22 Posts
Top