A Step by Step bare bone guide for Beginners - getting it right and sa

[Firestarter]

Oprime, just out of curiosity, how long have you been into marine fishkeeping?

[Oprime]

Hi Wilson

Yes that's the one for the time being.

[Oprime]

PH & KH & ACIDS & DECOMPOSITION

Carbonate Hardness (KH)

This is an area where many people get confused. One of the reasons the term alkaline is avoided a bit and the term Basic is used for the pH scale is because this reading is measuring the alkalinity of the water. It is not the same as alkaline.

The alkalinity is a measurement of the waters buffering ability, or its ability to absorb and neutralise acid. Clearly the more alkalinity or the higher the Carbonate Hardness of the water the less likely you will incur pH swings in the water. It is therefore important to get this figure reasonably high to stabilise the water.

When decomposition occurs acids are produced and these leech into our aquaria. This results in a drop in PH. Over stocking is also a factor.

PH levels of 7.5 to 8.5 are considered optimal for healthy nitrification of ammonia, and nitrites, as nitrification rates are rapidly depressed as the pH is reduced below 7.0. At 6.0 basically all nitrification ceases!

During the nitrification process carbonates are used by the aquarium to counter acids produced during nitrification (or other organic breakdown), however without an adequate KH this can become critical in crowded aquariums with low pH, thus allowing for a rise in ammonia and nitrites, sometimes to toxic levels.

However the flip side of low pH is that ammonia is converted to non toxic ammonium at lower pH, but keeping a low pH/KH that suppresses nitrifying bacteria can be a double edged sword where by a simple procedure such as a water change with slightly higher pH water can result in an immediate conversion of ammonium (NH4) to deadly ammonia (NH3) with disastorous results. This low pH, poor nitrifying environment also easily allows for the growth of pathogenic Fungi/Saprolegnia.

This is often misunderstood by some aquarists, who keeping adding cycling products, changing water, or anything else in a desperate attempt to lower ammonia/nitrites when the problem is a low pH/KH in a crowded aquarium that does not allow for adequate nitrification by chemolithotrophic nitrifying bacteria.

*DO maintain carbonate hardness (KH), especially when cycling a new tank, as the process of cycling will use carbonates and without adequate carbonates (KH) your pH can crash which will slow the establishment of nitrifying bacteria. I understand that Deltec Salt Mix has a higher KH composition which makes it ideal for use at the initial stages for new tanks.

[kianhl]

the motivation of author statement above were height playing more significant or dominant role versus length in deciding glass thickness. Let consider when both object having same volume but one taller and the other one longer, which one easier to tilt? Will derive more when free... Just share my tot... Cheers

As I promise to derive more.... Below r the general convention for glass thickness calculation, as you can see the length taking account in term of constant ratio (β) versus height, therefore the impact would be negligible in normal condition unless exceed certain matrix.

But on the other hand, look at the Height (H) in the notation, it play dominant effect as one of the key variable.

Pls find the notation below:

Glass thickness = ( (β x (H^3) X 0.00001)/B )^0.5

β = A constant ratio between length over height

H = height of Tank

Bending Stress ( B ):Tensile Strength / Safety Factor

Just share my tot..... Hopes above helps.... Cheers..

Hi everyone, I just joined SRC and I have so many questions to ask regarding marine fish aquarium. So I am feeling strange that my first post is not related, well... sort of.

I studied civil engineering in university and I think I can answer this question in layman terms, I hope.

If you have an adequately braced fish tank lengthwise, then only the height matters. The actual stress the glass is resisting is related to the height of the water. The stress profile is triangular in shape if you cut a section across the tank. This is called hydrostatic pressure and it is greatest along the base of the tank. So the higher the water level, the more pressure exerted. The centroidal force of this stress profile is 1/3 the height of the tank measured from the base. It creates a bending moment across an axis line 1/2 the water height. If the bending capacity of any material is reached, which for glass is very limited, fracture occurs. To resist this force, the thickness is the only factor you can play with.

For unbraced fish tank, the longer the length, the higher the deflection of the glass, all else being equal, including the water height. This deflection occurs at half the tank length and creates a nominal eccentricity from the original position. Again, the moment that results will test the capacity of the glass. This moment is not as crucial as the first one above.

Ok, that's it from me. Now back to reading more aquarium tips.

[CFOh]

Hi everyone, I just joined SRC and I have so many questions to ask regarding marine fish aquarium. So I am feeling strange that my first post is not related, well... sort of.

I studied civil engineering in university and I think I can answer this question in layman terms, I hope.

If you have an adequately braced fish tank lengthwise, then only the height matters. The actual stress the glass is resisting is related to the height of the water. The stress profile is triangular in shape if you cut a section across the tank. This is called hydrostatic pressure and it is greatest along the base of the tank. So the higher the water level, the more pressure exerted. The centroidal force of this stress profile is 1/3 the height of the tank measured from the base. It creates a bending moment across an axis line 1/2 the water height. If the bending capacity of any material is reached, which for glass is very limited, fracture occurs. To resist this force, the thickness is the only factor you can play with.

For unbraced fish tank, the longer the length, the higher the deflection of the glass, all else being equal, including the water height. This deflection occurs at half the tank length and creates a nominal eccentricity from the original position. Again, the moment that results will test the capacity of the glass. This moment is not as crucial as the first one above.

Ok, that's it from me. Now back to reading more aquarium tips.

Yup, Thanks for sharing, when talking about deflection, longer length higher α but the water height effect still dominant.

glass deflection = (α x water pressure x 0.000001 x depth^4) / ( E x t^3)

α = A constant ratio between length over height

E = Young's modulus

t = Glass Thickness

Pls find below the main effect simulation on the effects of Height and Length Versus deflection factor base on above formula. As we can see the Height effect change the deflection rate significantly versus the rate of deflection changing on Length factors. (notes, they may have interaction effects involve which not explain here).

Cheers...

[Speedwagon]

I'm worry after reading about the thickness of the glass. I'm currently using a 4ft (120x55x60) 12mm thick glass tank WITHOUT brace! Do you think this is ok to withstand the pressure in long run? I really don't want to see it give way!!!

Many thanks for the advise.

[Oprime]

It should be fine. Don't worry. You will be shocked if i tell you the thickness of my 2 foot marine tank.